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					Science 9
Chapter 19 – Simple Machines


19.1 Forces

     •   A force is a push or a pull

  Force effects – A force may:
     1. Cause a change in an objects shape
     2. Set a stationary object in motion
     3. Speed up a moving object
     4. Slow down a moving object
     5. Stop a moving object
     6. Change the direction of a moving object - Any object in motion will continue in
         motion unless a force acts in the opposite direction

  o Any motion that results depends on the size of the force and the mass of the object

  Unbalanced forces:
     One object is exerting a greater force than the other object. This results in one
  object moving
        o Push on a book – the force from your body is greater than the force of
           friction so the book will move in the direction of the greater force (the
           direction you are pushing)
        o Tug of war

  Balanced forces:
     Two objects are exerting equal forces on each other. The objects don’t move.
        o Push against a wall, the force from your body equals the force in the opposite
           direction, the wall doesn’t move

  Types of forces:

  1. Friction – Always resists motion when one material rubs against another caused by
     rough surfaces getting caught on each other




     Puck on smooth surface                     Puck on rough surface
     (little friction)                          (little friction)
     2. Gravity    – Another force which results between any two objects attracting each
        other
             •     Gravity can speed things up going downhill, or slow things down going uphill
             •     You are attracted to the earth because of gravity
             •     The force of attraction between things is measure in Newtons (N), named
                   after Sir Isaac Newton
               •   One Newton (N) force is the equivalent of an orange pushing down on your
                   hand



Mass and Weight

 •    Mass is the amount of matter an object contains usually measured in kg or g
 •    Weight is the amount of force that gravity exerts to attract an object. Gravity
      exerts a force of about 10N on each kg of mass
 •    If you know the mass of an object, you can find the force of gravity.

               F = m x g (g = speed of gravity = 10 m/s2)



       Ex. For a 3 kg object,
       F = (3 kg)(10 m/s2)
       F = 30 kg m/s2 = 30 N



  The force of gravity is 10N per kg on earth,
  The force of gravity is 1.7N per kg on the moon,
  The force of gravity is 25N per kg on Jupiter.

For a 54kg person, fill in the table below:



                       Earth             Moon      Jupiter
       Mass            54kg              54kg       54kg
      Weight           540N              90N       1350N



Do Review questions 19.1       Pg. 414
19.2 Force and Work

  Force is measured using a spring scale (units are Newtons)

  Work – Transfer of energy to an object
       • Depends on the size of the force used and the distance the object moves



           W =        F      x    d
                                                                   W
        (Joules) = (Newtons) x (metres)

                                                               F       d



        •   One Joule is the amount of work done when a force of one Newton moves an
            object one metre ( 1J = 1 Nm)



   Ex. A person uses a force of 200 N to push a box 1.5m. How much work was done?

     1. Write down the data you know, and the info you need to find out

     F = 200 N
     d = 1.5 m
     W=?

     2. Write down the equation

     W=Fxd

     3. Substitute and solve with units

     W = (200N)(1.5m)
       = 300 N m = 300 J

     4. Make a final statement answering the question

     The work done was 300J
Science 9 – Forces and Machines                    Name:______________________
                                                   Date:___________ Block:______



  1. Give the full name of the standard unit for force, as well as its symbol

  2. Use a diagram with arrows to describe the following forces. (Use the same diagram
     for a-d, and the same scale for all of your four force arrows)
     a) 5N acting upwards                    b) 10N acting downwards
     c) 8N acting to the left                d) 3N acting to the right

  3. How much force is needed to lift
     a) a 1kg bag of apples  b) a single 100g apple       c) a 10kg box of apples

  4. Which would probably require the greater force, lifting a 50kg sack of potatoes or
     dragging it along the floor? Why?

  5. Which of the following are measure of force, and which are measures of mass?
     a) 60N      b) 45kg      c) 32t      d) 800N

  6. Calculate how many joules of work are done in each case
     a) F = 5N, d = 0.5m      b) F= 16N, d = 30m         c) F = 0.5N, d = 0.1m

  7. A physiotherapist exerts 18N of force to move a patient’s arm a distance of 0.6m.
     Calculate the work done on the arm.

  8. A bulldozer exerts a force of 6000 N to move a rock a distance of 45 m. How much
     work was done on the rock?

  9. A teenager’s hand moves an average distance of 7cm when lifting the pull tab on a
     can of juice. The average force exerted on the tab is 8 N. How much work must the
     teenager do to open ten cans of juice?

  10. A plasterer’s helper exerts a force of 500 N to hold a sheet of drywall still while
      someone else nails it in place. How much work did the helper do on the drywall?

  11. A reporter picks up a microphone having a mass of 100g.
      a) How much force is required?
      b) How much work is done when the microphone is lifted a distance of 0.10m?
19.3 Doing Work with Machines

    •    Simple machines are an extension of the topic energy which was begun in Sc 8 with
         heat, light and sound and will be followed in Sc 10 with electricity and magnetism


o A simple machine is anything that makes it easier or more convenient to do work.
        o 3 ways a simple machine can do this is by:


        1. letting you exert less force (Multiplying a force)
                 ex. a car jack allows you to lift a car with less force
        2. letting you do work faster (Multiplying speed)
                 ex. Bicycle pedals require less distance to be pushed than the distance the
                           tire turns in one revolution
        3. letting you exert the force in an easier direction (Changing direction of a force)
                 ex. A flag can be lifted up a flagpole by pulling down.



o   Machines do at least one of the following jobs:

    1. Transfer forces from one place to another
        • Hand generator transfers from hand to motor
    2. Transform energy from one form to another
        • Hand generator transforms mechanical E to light E
    3. Change the direction of a force
        • Pulley changes downwards pull to an upwards pull
    4. Multiply speed or distance
        • Bike pedals multiply the speed of the tire
    5. Multiply force
        • Little force on lever lifts a large weight



Mechanical advantage is the amount a machine can multiply a force

           Mechanical advantage (MA) = Load force (FL) / effort force (FE)

                 o Where load force is the force without the machine (the force the
                   object has, usually FL = m x g)
                 o Effort force is the force with the machine (the amount of force the
                   machine exerts, usually given)
Ex. Lifting a box requires 110N, but if you use a pulley, you only use 10N. What is the
mechanical advantage?

      1. Write what you know and what you need to find out

      Load force = 110 N
      Effort force = 10 N
      Mechanical advantage = ?

      2. Write the equation

      Mech adv = Load force / effort force

      3. Substitute into the equation

      Mech adv = 110N / 10N = 11

      4. Make a final statement

      The mechanical advantage is 11
Science 9 – Forces & Machines                     Name:______________________
                                                  Date:___________ Block:_______

  1. What is a machine?




  2. Lifting a friend in a wheelchair straight up onto a porch requires a force of 900N.
     With a ramp, the effort force needed is only 150N. Calculate the mechanical
     advantage of the ramp.




  3. To have repairs made on its underside, a 40 000N railway car is pulled up a ramp and
     onto a raised platform. The effort force needed is only 5000N. Calculate the
     mechanical advantage of the ramp.




  4. A 3200N boat is towed up a boat ramp. The truck pulling the boat exerts an effort
     force of 500N. Calculate the mechanical advantage of the boat ramp.




  5. A nurse uses a force of 200N to push a wheelchair up a ramp to the door of the
     hospital. The wheelchair and patient weigh 800N. What is the mechanical advantage
     of the ramp?




  6. A cook does 1000J of work on a hand-operated food grinder. The grinder does
     750J of work on the food. Calculate the efficiency of the food grinder.




  7. A pulley system is used to lift a 1200N engine a height of 0.9m. The mechanic
     exerts an effort force of 200N and pulls the rope a total distance of 6m. Calculate
     the efficiency of the pulley
19.4 - The Six Simple Machines:

  1. The inclined plane

         •   A sloping surface like a ramp
         •   The more gentle the slope, the greater the mechanical advantage
         •   A hiking trail is a ramp




  2. The wedge

             •   A wedge is like a ramp, put is pushed into or under an object
                    o Can be used to split objects or prevent an object from moving
             •   The longer and narrower the wedge, the greater the M.A.
             •   Examples are needles, knives, axes




  3. The screw

             •   A screw is an inclined plane wrapped around a rod
             •   Able to enter hard objects like wood easily
             •   Corkscrews, jar lids are also screws
  4. The lever
          • The lever is a bar supported at one point called the
             fulcrum and rotates about this point
          • There are 3 different ways levers can be arranged


                                                                                  E
                                 E




 E                    L                          L                  L



First class lever                    Second class lever                 Third class lever
Ex. hammer (pulling                  Ex. Bottle opener/                 Ex. Fishing Rod/
out a nail), prybar                  wheelbarrow                        human arm




  Multiplies Force              Multiplies Force               Multiplies distance and speed



  Mechanical Advantage/Levers Example:


                                                     Mechanical adv = load / effort
                                                                  = 3600N / 600N
                      Load of                                     =6
Effort of             3600N
600N


  The location of the fulcrum in this 1st class lever will determine how much mass you
  can lift. The closer the fulcrum to the load, the less effort you will have to apply
  (or the more mass you could lift)
Ex.                               FL = 3600 N


           FE = 600 N




In order to raise the bus 0.1m, the person must push the lever down 0.6m.


FL =                      FE =
dL =                      dE =
WL =                      WE =




* Thus, the amount of work done by the lever is no greater tha the amount of work done on
the lever. Work is not saved by using a simple machine, actually extra work is often needed
to overcome friction between the machine’s moving parts.



      5. The wheel and axle

              •   A large diameter wheel is attached to a small diameter axle or shaft
              •   Screwdriver, pencil sharpener and a hand drill are examples
   6. The pulley

      •   A pulley is a rope looped around a support or wheel




                  E                              E

           L

                                            L
      Single fixed pulley          Single moveable pulley




      •   These pulleys change direction of applied force
      •   More complicated pulley systems multiply force and change direction of the force


o In a fixed pulley, the load and effort forces are the same.


o In a moveable pulley, all strings in the pulley share the load with the exception of the
   string that is pulled
      o If the string is pulled upwards, it is also included in sharing the load.
      o If the string is pulled downwards, it does not share the load, its only function is
          to change direction of the force (to make it easier to pull).


Ex. If there are two strings, a load force of 100N will require an effort force of 50 N on
each string. The mechanical advantage is 2.




WE = FE x dE                WL = FL x dL
   = 50N x 2m                    = 100N x 1m
          Both are equal to 100 Joules                                              100N


(Remember that the movable pulley multiplies force, but does not reduce the work needed
to raise the load. In order to lift the load 1m, the effort force must pull the rope through
2m.)
19.5 - Efficiency of Machines



   •    The efficiency of a machine is a calculation of the work done by a machine
        (work output) as a percentage of the work needed to operate it (work input)



The work done by a machine when it moves a load is called its work output (To determine
this you must know the load Force and the load Distance (because W = F x d)


The work done on a machine is called its work input (To determine this you must know the
effort Force and the effort Distance (because W = F x d)



       Efficiency = Output / Input x 100%



Ex. The energy in a fuel is 400kJ. When the fuel is burned in a motor, it produces 100kJ
of energy. What is its efficiency?



       Efficiency = output / input x 100%
                      = 100kJ/400kJ x 100% = 25%

       The energy is lost as heat and friction. Internal combustion engine cars are not very
       efficient.
Sc 9 PROBLEMS INVOLVING WORK                             Name_________________
                                                         Date__________ Period___

Problems involving work are of three types. (1) You may be given the force and distance
and be asked to find work. (2) You may be given the work and distance and be asked to
find the force. (3) You may be given the force and work and be asked to find the distance.



  TYPE 1: FINDING WORK, GIVEN FORCE AND DISTANCE.
  PROBLEM: An object has a force of 5.0 N applied to it and moves a distance of 4.0 m.
             Find the work done.
  SOLUTION: The formula for work is       Work = force X distance
             Thus,     W = 5.0 N x 4.0 m = 20 N•m = 20 J

  TYPE 2: FINDING FORCE, GIVEN GIVEN WORK AND DISTANCE
  PROBLEM: 20 J of work are done by a constant force when it moves an object 4.0 m.
             Find the constant force on the object.
  SOLUTION: W = F x d or d = W = 20.0 N•m           = 5.0 N
                              F          4.0 m

  TYPE 3: FINDING DISTANCE, GIVEN WORK AND FORCE
  PROBLEM: 20 J of work are done on an object when a constant force of 5.0 N is
             applied. Find the distance the object moves.
  SOLUTION: W = F x d or d = W = 20.0 N•m           = 4.0 m
                               F         5.0 N



Now try doing the following questions:


1. Calculate the work done in each of the following examples.
   (a) Force = 4 N, distance = 2 m          (c) Force = 20 kN, distance = 3.0 m




   (b) Force = 120 N, distance = 3.60 m     (d) Force = 8.0 N, distance = 150 cm
2. Calculate the force exerted in each of the following examples.
   (a) Distance = 20 m, work done = 500 J       (c) Distance = 3.5 m, work done = 105 J




   (b) Distance = 480 cm, work done = 288 J    (d) Distance = 4 km, work done = 20 kJ




3. Calculate the distance through which the force is exerted in the following examples.
   (a) Force = 40 N, work done = 80 J      (c) Force = 400 N, work done = 30 kJ




   (b) Force = 2.2 N, work done = 660 J     (d) Force = 2.5 kN, work done = 7.5 kJ




4. A force of 15 N is applied to a toy car and moves it 4.0 m. How much work is done?




5. A car travels along a level road a distance of 1.5 km. The forward force exerted by the
   road on the car is 200 N. Calculate the work done on the car in Joules.




6. A force of 350 N is required to push a piano having a mass of 400 kg. How much work is
   done to push the piano 5.0 m across the floor.




7. A car accelerates from 0 to 100 km/h in 8 seconds. It covers a distance of 100 m in
   this time. the engine does 300 kJ of work to accelerate the car. What is the average
   force exerted by the engine?
Sc 9 FORCE, WORK AND MACHINES PROBLEMS                       Name_________________



1.   A hiker places a 12 kg backpack on the ground in order to open the door of a cabin.
     (a) How much force is required to pick up the backpack again?




     (b) How much work must be done on the backpack to raise it from the ground to the
     floor of the cabin, a distance of 0.3 m?




2. Four movers have to raise identical crates onto the back of a truck 1.2 m high. The
   first mover lifts the 850 N crate straight up and onto the truck. The second mover
   uses a 4 m ramp and exerts a force of 285 N. The third mover uses a very long ramp
   of 10 m and exerts a force of 140 N. The fourth mover tries to lift the crate but fails.

     (a) Which mover exerts the largest force?




     (b) Which mover does the most work?




     (c) Which mover does the least work?




3. A crane lifts a 500 kg box 10 m in the air. How much work is done?




4. An engine does 25 000 J of work lifting a 2000 N box. How far is the box lifted?
5. Four students run up a set of stairs 4 m high. The table below shows their weights and
   times.
                         STUDENT          WEIGHT          TIME
                            A              450 N          3.6 s
                            B              800 N          6.4 s
                            C              600 N          5.0 s
                            D              500 N          4.0 s


    (a) Which student exerts the largest force?



    (b) Which student does the least work?



6. An inclined plane is used to push a 500 N load to the bed of a truck, a height of 2.0 m.
   The sloping surface is 10.0 m long, and the mover pushes with an effort force of 100 N.

   (a) Calculate the work output (work done by machine on load).




   (b) Calculate the work input (work done on machine by mover).




   (c) Calculate the efficiency of the machine.




7. A screw-type pump is used to raise 200 kg of water a distance of 3.0 m. The handle of
   the pump is turned with an effort force of 40 N a total of 1200 times tracing a circle
   of 20 cm circumference each time.
      (a) Calculate the work output.



       (b) Calculate the work input.



       (c) Calculate the efficiency.
8. A farmer uses a wheel-and-axle to raise a 1000 N feed sack to the loft of a barn, a
height of 8.0 m. The handle of the wheel-and-axle must be turned 150 times to do this
using an effort force of 100 N each time. On each turn, the handle traces out a circle 60
cm in circumference. Calculate the machine’s efficiency.




MORE FORCE AND WORK PROBLEMS! (Be sure to show your work.)

1. How many newtons of force will it take to lift an object with a mass of 250 grams?




2. A force of 50 N is needed to lift an object. What would the mass of this object be?




3. What force would be needed to slide a 2000 g book across a smooth table?




4. A boy pushes against a 4000 kg wall with a force of 500 N. How much work was done?




5. A garage door opener exerts a 200 N force to move a door 2 metres. How much work
   has been done?




6. A 100 g object is lifted 5 metres. How much work has been done?




7.                            800 N
                                          (a)   Work output = ?
             70 kg                        (b)   Work input = ?
                                          (c)   Load distance = ?
                     20 cm                (d)   Mechanical Advantage = ?
                                          (e)   Can the job be done?
Sc 9 Efficiency WS                             Name: ____________________
                                                  Date:_______ Period ____

1. A cellular phone charger uses 4.83 J of energy per second. 1.31 J of this end up stored
   in the battery as chemical energy.
   a) What is the efficiency of the charger?
   b) What % of the energy is “lost” to other forms?
   c) What other forms could the “wasted” energy be converted to?

2. A solar panel receives 500 J of energy from the sun. 280 J of this ends up as heat, 105
   J transmit through the panel as light, 40 J of light energy are reflected off the panel,
   and 75 J are captured and converted to electricity.
   a) What is the efficiency of the solar panel?
   b) What % of the energy is lost to heat?
   c) How many J of energy are lost in total?
   d) What is the total % of lost energy?

3. A windmill is hit by air with 20,000 J of energy per second. The function of the
   windmill is to convert the energy to electricity, and 5,000 J/sec are transferred to this
   form. What is the efficiency of the windmill?

4. Coal is burned to make electricity in a power plant. A coal-burning power plant is 33%
   effective. If a piece of coal containing 2500 J of stored chemical energy is burned,
   how much useful electricity can be harnessed?

5. A hydroelectric power plant converts the energy of falling water into electricity. The
   conversion is 90% effective. If 500,000 J of electrical energy are produced, how much
   gravitational energy did the water initially have?

6. Different kinds of light bulbs have different efficiencies. 150 J of energy are supplied
   to each of 2 light bulbs. The incandescent (regular) light bulb puts out 1.95 J of light
   energy, and the compact fluorescent bulb puts out 30 J.
      a) What is the efficiency of each bulb?
      b) What would be the advantages of making a bulb more efficient?

7. Consider the list of energy conversions & their efficiencies on p. 127 of your text.
      a) Rank the 3 product forms of energy (light, heat, mechanical) from most to least
      efficient to produce. You’ll have to generalize.
      b) Can you explain why your answer for (a) might be logical/expected?
Sc 9: Machines & Mechanical Advantage                    Name___________________

           Formulae to know:          M.A. = FL / FE,          FL x dL = FE x dE

1. A 61.2kg block is pulled up a ramp. The force required to do this is 200N.
      a. What force would be needed to lift the block?
      b. What is the mechanical advantage?
      c. What is the function of the machine?

2. A 5kg block is pushed up a ramp with a force of 7N until it reaches a height of 2m.
         a. What is the load force of the block?
         b. How long is the ramp?

3. A 500N block is placed on one end of a lever. A force of 200N is applied to the other
   side.
         a. What is the mechanical advantage?
         b. If you push the right side of the plank down by 50cm, how far will the block
            be lifted?
         c. What is the function of this machine?

4. A lever is used to lift a 9,000,000 N car with a 2,178,000 N applied force.
         a. What is the mechanical advantage?
         b. How far must you move the free end of the lever in order to lift the car
             50cm off the ground?

5. To lift a 10 N object with your hand/arm, a 35 N force is applied by muscles near your
   elbow to lift your entire arm. This is an example of a 3rd class lever.
          a. What is the mechanical advantage?
          b. If your arm moves 9 cm near the elbow, what distance will your hand move?
          c. What is the machine function of your arm?

6. A 400N child and his 350N friend are playing on the see-saw. If the 400N child sits
80cm from the centre of the see-saw, where will his friend need to sit to balance it?

7. A girl pushing a load in a wheelbarrow is able to exert an upward force of 140N on the
handles. The load is 25 cm from the wheel, and the handles are 75 cm from the wheel.
                a) Draw a diagram of this lever:
                b) What maximum load can she carry in Newtons and in kg?
Levers Worksheet                                            Name___________




    The fulcrum is between the                                    The effort force is between
                                 The load force is between the
     effort force and the load                                      the load force and the
                                 effort force and the fulcrum.
              force.                                                       fulcrum.

                                 Function:
  Function:                                                      Function:




Identify which classes of levers are being used in each of the following machines:

Scissors                  __________________________________________


Tweezers                  __________________________________________


Wheelbarrow               __________________________________________


Nut cracker               __________________________________________


See Saw                   __________________________________________


3-hole punch              __________________________________________

Pliers                    __________________________________________


Stapler                    ___________________________________________


Fishing Rod                _________________________________________
Science 9 - PULLEYS                                              Name:______________



In each of the following pulley systems, the load force is 10 N and the load force moves
0.1 metre. Calculate the effort force, effort distance, mechanical advantage, number of
support strings, and function of each of the systems, then fill in the data table on the
following table.




A.                         B.                               C.

                                             Effort
                                             Force


                                                                               Effort
              Effort
                                                                               Force
              Force



 Load
                                     Load
 Force                                                                 Load
                                     Force
                                                                       Force



D.                         E.                               F.

     Effort
     Force



                                              Effort
                                              Force
                                                                  Effort
                                                                  Force

              Load
              Force

                                                                           Load
                                     Load                                  Force
                                     Force
             SYSTEM A SYSTEM B SYSTEM C SYSTEM D SYSTEM E SYSTEM F
Effort
Force
(N)

Effort
Distance
(m)

Mechanical
Advantage

Number of
Support
Strings

Function:
 multiply
 force
multiply
distance
change
direction
transfer
energy
             FORCE, WORK AND MACHINES PROBLEMS
                                        - ANSWERS -
1.   How much force is needed to lift:
     (a) a 1 kg bag of apples?    10 N
     (b) a single 100 g apple? 100 g / 1000 g x 10 N / 1 kg = 1 N
     (c) a 100 kg box of apples? 10 kg x 10 N / 1 kg = 100 N


2. Calculate the work done when a student exerts a force of 400 N to push a stalled
   motorcycle from a
   busy highway onto a quiet street, a distance of 500 m.
     W = F x d = 400 N x 500 m = 200 000 Nm = 200 000 J

3. A teenager’s hand moves an average distance of 7 cm while lifting the pull tab on a can
   of juice. The average force exerted on the tab is 8 N. How much work must the
   teenager do to open ten cans of
   juice?
     W = F x d = 8 N x 0.07 m = 0.56 Nm = 0.56 J

4. A hiker places a 12 kg backpack on the ground in order to open the door of a cabin.
   (a) How much force is required to pick up the backpack again? F = 12 kg x 10 N/1 kg =
     120 N
     (b) How much work must be done on the backpack to raise it from the ground to the
     floor of the
         cabin, a distance of 0.3 m?
        W = F x d = 120 N x 0.3 m = 36 Nm = 36 J

5. Four movers have to raise identical crates onto the back of a truck 1.2 m high. The
   first mover lifts the 850 N crate straight up and onto the truck. The second mover
   uses a 4 m ramp and exerts a force of 285 N. The third mover uses a very long ramp
   of 10 m and exerts a force of 140 N. The fourth mover tries to lift the crate but fails.
   (a) Which mover exerts the largest force?
        Mover 1: F = 850 N; Mover 2: F = 285 N; Mover 3: F = 140 N; Mover 4: F = less than
     850 N
        Therefore, Mover 1 exerts the largest amount of force.
     (b) Which mover does the most work?
        Mover 1: W = F x d = 850 N x 1.2 m = 1020 J; Mover 2: W = 285 N x 4 m = 1140 J;
        Mover 3: W = 140 N x 10 m = 1400 J; Mover 4: W = 850 N x 0 m = 0 J
        Therefore, Mover 3 does the most work.
     (c) Which mover does the least work?
        Mover 4 does the least work because he does not move the object.
6. A crane lifts a 500 kg box 10 m in the air. How much work is done?
   500 kg = 5000 N therefore W = F x d = 5000 N x 10 m = 50 000 Nm = 50 000 J

7. An engine does 25 000 J of work lifting a 2000 N box. How far is the box lifted?
   d = W/F = 25 000 Nm / 2000 N = 12.5 m

8. Four students run up a set of stairs 4 m high. The table below shows their weights and
   times.
   (a) Which student exerts the largest force? Student B at 800 N
   (b) Which student does the least work?
            Student A: W = F x d = 450 N x 4 m = 1800 J

An inclined plane is used to push a 500 N load to the bed of a truck, a height of 2.0 m. The
    sloping surface is 10.0 m long, and the mover pushes with an effort force of 100 N.
    (a) Calculate the work output (work done by machine on load).
       W = F x d = 500 N x 2.0 m = 1000 Nm = 1000 J
   (b) Calculate the work input (work done on machine by mover).
       W = F x d = 100 N x 10.0 m = 1100 Nm = 1100 J
   (c) Calculate the efficiency of the machine.
       Efficiency = work output/work input x 100% = 100 J / 1100 J x 100% = 91%

10. A screw-type pump is used to raise 200 kg of water a distance of 3.0 m. The handle of
    the pump is turned with an effort force of 40 N a total of 1200 times, tracing a circle
    of 20 cm circumference each time.
    (a) Calculate the work output. W = F x d = 2000 N x 1.0 m = 6000 Nm = 6000 J
    (b) Calculate the work input. W = F x d = 1200 x 40 N x 0.2 m = 9600 Nm = 9600 J
    (c) Calculate the efficiency.
       Efficiency = work output/work input x 100% = 6000 J / 9600 J = 62.3%

11. A farmer uses a wheel-and-axle to raise a 1000 N feed sack to the loft of a barn, a
    height of 8.0 m. The handle of the wheel-and-axle must be turned 150 times to do this
    using an effort force of 100 N each time. On each turn, the handle traces out a circle
    60 cm in circumference. Calculate the machine’s efficiency.
   Work Output = F x d = 1000 N x 8.0 m = 8000 Nm = 8000 J
   Work Input = 150 x F x d = 150 x 100 N x 0.6 m = 9000 Nm = 9000 J
   Efficiency = work input/work output x 100% = 8000 J / 9000 J x 100% = 88.9%
                            SIMPLE MACHINES FLOWCHART
                                                   defined as



                                                   functions
              defined as                              to


                                                     does
  SIMPLE                      6                      work
                            types
 MACHINE
                                                   functions
              5 functions                             to

                                                                      made up of

                                                     does
                                                     work

                                                   functions
                                                      to


                                                   made up
                                                     of

                                                      functions to




                                                    defined as


                                                       3 types

                                                                 functions to
                                                                                     function to


amount
multiplied
determines                                         defined as

                                        3 types


 calculated
     by
                                    functions to                      functions to    functions to
                         SIMPLE MACHINES FLOWCHART
INSTRUCTIONS: Complete the Simple Machine flowchart by cutting and pasting the terms below into
their correct places. Add in your own examples.
                                                                          a sloping surface
        screw                               fulcrum is between effort    along which a load
                                                force and load force          is moved
   transfer energy       inclined plane
  from one form to
                                                     by being pushed
       another                                                               large diameter disk firmly
                                                    into another object
                                                                                 attached to a small
                             load force
                                                                                    diameter shaft
                            effort force                 movabl

                                                                                        mechanical
  a device that helps     effort force is between           multiply force              advantage
    people do work        load force and fulcrum
      more easily
                                                         multiply force or multiply           fixed
                             multiply force                  distance or speed
    transfer forces
  from one place to                                                                       wedge
                               wheel and axle            a rope or cable that is
        another                                         looped around a wheel
                                                                                         change the
                                 multiply force
                                                                   lever               direction of the
     multiply speed or                                                                      force
         distance
                              load force is between
                                                                                    lift heavy loads
                             effort force and fulcrum
                                                                  multiply distance & speed
       multiply force

                                   an inclined
    by moving into or                                          combination
                                      plane
    through an object               wrapped                                           multiply force
                                  around a rod
                                                               change direction


                                  a bar that is supported at
       multiply force                one point (fulcrum)                                  pulley
ANSWERS

 a device that helps                                          defined as
                                                                               a sloping surface
   people do work                       inclined plane                        along which a load
     more easily                                                                   is moved
                                                              functions
                                                                 to                   multiply force
               defined as


                                                                does          by being pushed
   SIMPLE                      6           wedge                work         into another object
                             types
  MACHINE
                                                              functions
                                                                 to                   multiply force          an inclined
               5 functions
                                                                                                                plane
                                                                                 made up of                    wrapped
    transfer forces                                                           by moving into or              around a rod
                                                                does
  from one place to                         screw               work          through an object
        another
                                                              functions
                                                                 to                   multiply force
   transfer energy
  from one form to                                                                large diameter disk firmly
                                                              made up
       another                         wheel and axle           of                    attached to a small
                                                                                        diameter shaft
                                                                functions to
                                                                                              multiply force or multiply
      change the
                                                                                                  distance or speed
   direction of the
        force
                                                               defined as          a rope or cable that is
                                           pulley
                                                                                  looped around a wheel
  multiply speed or
                                                                  3 types            fixed       movable     combination
      distance
                                                                            functions to
                                                                                                              function to
   multiply force                                                             change direction         multiply force
 amount
 multiplied
 determines                                                   defined as         a bar that is supported
                                            lever
                                                                                 at one point (fulcrum)
     mechanical                                     3 types
     advantage
  calculated                    fulcrum is between effort        load force is between             effort force is between
      by                           force and load force         effort force and fulcrum           load force and fulcrum
      load force                             functions to                        functions to                   functions to
     effort force                    lift heavy loads               multiply force              multiply distance & speed
Sc 9 Forces Worksheet                         Name__________

FORCES FLOWCHART


defined as    affected by                                  occurs when

                  opposed or                  opposed by
                   aided by


                                     needed to

                   units
                 measured in   FORCE          defined as

                                     when it moves
                                     an object through
                                     a distance




                                 amount
                                  done
                                depends on




                                the formula
                                for work is




                                      units measured in




                                       can be equated to
INSTRUCTIONS: Use the following boxes to fill in the flowchart on the previous page. Either copy
them out or cut and paste them.



    mass of objects and             the attraction           the distance                   Joules (J)
     distance between                between all            object moves
           objects                     objects
                                                                                 friction

    Newton (N)              make an
                          object move                                        one material rubs
                                                                            against the surface
          gravity                                                               of another
                                    Work is done

                                                                                      1 J = 1 N .m
                                                      amount of
      Work = Force x distance
                                                     force exerted


                                a push or a pull
FORCES FLOWCHART ANSWERS



  the attraction      mass of objects and                                                 one material rubs
   between all         distance between                                                  against the surface
     objects                objects                                                          of another

  defined as                 affected by                                                           occurs when

                                  opposed or       make an           opposed by
                 gravity                                                                friction
                                   aided by      object move


                                                         needed to


               Newton (N)          units
                                 measured in    FORCE                defined as      a push or a pull
                                                         when it moves
                                                         an object through
                                                         a distance

                                                 Work is done


                                                     amount
                                                      done
                                                   depends on
                                 amount of                            the distance
                                force exerted                        object moves

                                                   the formula
                                                   for work is


                                              Work = Force x distance

                                                          units measured in


                                                     Joules (J)

                                                           can be equated to



                                                   1 J = 1 N .m
PHYSICS 9 - Review                                          Name_________________


FORCES…(Chapter 5)

o Pushes and pulls are called forces. Examples of forces are gravitational force, pushing
   and pulling on an object, centripetal force (the force that pushes an object outward
   from a centre of rotation), and the force of friction.


o The newton (N) is the unit used to measure force.


o 1 kg = 10 N (because F = ma and the acceleration due to gravity is 9.8m/s2, so F = 1kg x
   9.8m/s2 = 9.8 N – so we just say 10N)


o Gravity is the force any object exerts on every other object.


      o Mass is the amount of matter in an object. The force of gravity on you depends
         on: (a) your mass, (b) the mass of the object attracting you, and (c) how far away
         you are from the object attracting you.


o Friction is the force that resists motion whenever one material rubs against another.
   In other words, it is the force that tries to stop anything from moving. Any time there
   is friction, some mechanical energy is transformed to thermal energy. A lubricant is
   any material that can be used to decrease friction.


WORK… (Chapter 5)

o If we exert a force on something and move it, we are doing work. The amount of work
   done is calculated by multiplying the force exerted (in Newtons) by the distance the
   object is moved (in metres). Work = force x distance. A joule is the unit used to
   measure work done or energy transformed. (1 joule = 1 newton metre) The amount of
   work done is equal to the amount of energy transformed.
WORK = FORCE x DISTANCE
(Force – Newtons, distance = m, work = Nm = J)


You writing notes, although you think you are doing a lot of work, are actually doing very
little, as your pencil is moving only a small distance!



MACHINES…

o Simple machine - anything that makes it easier or more convenient to do work. Three
   ways a simple machine can do this is by:
           1. Multiplying a force
             ex. a car jack allows you to lift a car with less force
           2. Multiplying speed
             ex. Bicycle pedals require less distance to be pushed than the distance the
                    tire turns in one revolution
           3. Changing the direction of a force
             ex. A flag can be lifted up a flagpole by pulling down.


The number of times a machine can multiply effort force is the mechanical advantage:
           MA = load force (FL)/effort force (FE)


   o The six types of simple machines are:
           Inclined plane; wedge; screw; lever; pulley; wheel and axle


   o With a simple machine, you always make work easier and more convenient, but you do
      not do less work, you actually end up doing a tiny bit extra, here’s why…


The work done by a machine when it moves a load is called its work output      WL = FL x dL


The work done on a machine is called its work input         WE = FE x dE


Efficiency of a machine = (work output of a machine) / (work input to a machine) x 100%
                         19-1      Chapter 19 - Assignment #1
                                Doing Work with Machines



1. What is a machine? Give an example of a machine. (pg 418)

2. List the 5 functions of a machine. (pg 419) Also, give 3 examples of machine functions
(pg 420, left side)

3. What is mechanical advantage? (pg 420)

4. Give the equation for mechanical advantage. (pg 420)

5. Explain what load force is and what effort force is. (pg 420)

6. Why does a ramp seem like getting something for nothing, but is really not the case.
(pg 420)

7. What is true for all simple machines? (pg 420)

8. Name the 6 simple machines. (pg 422, top)

9. What is a ramp? (pg 422)

10. What happens when the slope gets more gentle? (pg 420)

11. What is the function of an inclined plane? (pg 422)

12. What is a wedge and what is itsÕ function? (pg 423)

13. How can you make the mechanical advantage of a wedge greater? (pg 423)

14. Give 4 examples of wedges. (pg 423)

15. What is the simple machine called the screw and what is its function? (pg 423)

16. What is a lever? (pg 424)

17. Draw a diagram to show how the forces can be arranged in the 3 types of levers and
give an example of each of these types of levers. (pg 424 and 425)
18. Give an example where levers are used in pairs. (pg 425)

19. What is wheel and axle? (pg 426)

20. Draw a diagram of a wheel and axle. (pg 426)

21. What do wheel and axles do? (pg 425)

22. What is a pulley? (pg 427)

23. What are the 3 types of pulley systems and what is the function of each? (pg 427)

24. Draw a diagram of each of the 3 types of pulley systems. (pg 427)

25. Read pg 430. How are robots simple machines? (pg 431)

26. What must extra force be used to overcome in simple machines? (pg 431)

27. What is the efficiency of a machine? (pg 431)

28. State the 2 ways of calculating efficiency using equations. (pg 431)

29. What would be the efficiency of a machine with no friction? (pg 431)

30. How does work output in real machines compare to work input? (pg 431)

31. Why can machines not create work? (pg 432)
ENERGY… (Chapter 6)


An object has energy if it can make other objects move.

Energy is the ability to make things move
                o Ex. Magnets on paper clips
                o Tuning fork on water
                o Flowing water
                o Rolling carts
                o Rubber bands


If you lift your backpack weighing 20 N a height of 1 m to your shoulders, your backpack
   now has an additional 20N x 1m = 20Joules of potential energy stored which later can
   be used to do work


o The Law of Conservation of Energy says “Energy cannot be created or destroyed. It
   can be changed from one form to another, but the total amount of energy in the
   universe never changes.


Ex. How much energy is needed to raise the a load of 4000kg a distance of 300m? State
the answer in kJ.


    1. Change the mass to newtons




    2. Calculate the work done




    3. Determine the amount of energy required to do the work




    4. Change the energy units to kilojoules (1000J = 1kJ)
Types of Energy


• Mechanical:         the kind of energy an object has because it is moving
• Gravitational:      the kind of energy an object has when it is in position to roll, fall or
                      slide downhill
• Chemical:           the energy that is stored in chemical compounds, such as gasoline,
                      wood, coal, dynamite, and batteries
• Magnetic:           the form of energy that causes some kinds of metal to attract or
                      repel some metal objects
• Electrical:         the energy of moving electrical particles
• Thermal:            the energy an object has because its particles are moving in all
                      directions
• Light               the form of energy that you can see
• Elastic             the energy stored in an object whose shape is changed by
                      stretching, compressing, or twisting
• Nuclear             the energy stored in the central part of the atom
• Sound               the kind of energy that is produced when an object vibrates; energy
                      that you can hear


Potential and Kinetic Energy

Energy can be classified in two ways:

   1. Potential Energy – Stored energy
      • Wound up spring in a toy car which gets transformed into mechanical energy
      • A battery has stored chemical energy

   2. Kinetic Energy – the energy of anything in motion (kinetic means moving)
      • A moving car
      • A roller coaster
Gravitational, chemical, magnetic, electrical, elastic and nuclear are considered forms of
potential energy or energy which can be stored.


Mechanical, thermal, light and sound are forms of kinetic energy or energy which cannot be
stored.
Energy Transformations:


Transformation of energy occurs when energy is changed from one form to another.


                   Device                    Input energy                 Output energy

       1. Candle

       2. Drill

       3. Generator

       4. CD player

       5. Flashlight




o An energy converter is any apparatus that changes one form of energy into another.
     Energy converters change some energy into thermal energy through friction.




o Efficiency of an energy converter refers to the converter’s ability to transform large
     amounts of the original energy into useful energy. Efficiency can be calculated by:


                                    useful energy output
                  Efficiency =                                    x 100%
                                     total energy input


Do activity 6D - Energy flow through a car

ANSWERS to Fill in the table below:

            Device                    Input energy                  Output energy
1.   Candle                    Chemical                      Thermal, light
2.   Drill                     Electrical                    Sound, mechanical
3.   Generator                 Mechanical                    Light, electrical
4.   CD player                 Electrical, Chemical          Mechanical, sound
5.   Flashlight                Chemical                      Light, Electrical
HEAT – (Chapter 7)


Thermal Energy and Temperature

   •   Thermal energy is heat
   •   Heat and temperature are not the same thing.

Heat or thermal energy is the total energy of all the particles in an object
         • Depends on the size of the object, a pot of hot soup has more energy than a
            cup of hot soup

Temperature is a measure of the speed of the particles
        • Temperature does not depend on the size of the object, a cup and a pot of
           soup have the same temperature
        • Low temperature – slow moving particles
        • High temperature – fast moving particles
        • Thermometers measure temperature, either mercury or coloured alcohol
               o The Fahrenheit thermometer measures water freezing at 32o F
               o The Celsius thermometer measures water freezing at 0o C

Heat Transfer

   •   Heat transfer involves the movement of heat from a hot object to a cold one

   •   Conduction – Heat transfer in solids
          o A conductor is a substance that transfers heat well by the collision of
            particles (many metals are excellent conductors)

   •   Convection – Heat transfer in fluids
          o Fluids are liquids and gases that are poor heat conductors because particles
             are too far apart
          o Hot fluids rise

   •   Radiation – Heat and light come to us from the sun through empty space where
       there are no particles – energy that is transferred without particles is called radiant
       energy
          o Dark objects absorb energy well

   •   Preventing heat transfer – In order not to lose heat,
          o Insulators – slow down or prevent heat transfer – like in a thermos
The Kinetic Molecular Theory                               Name:_____________
                                                           Date:________ Per:___



_____________ means moving

_____________ are particles of matter

_____________ is used to explain observations

The kinetic molecular theory explains our observations of moving particles of matter




There are eight statements in the KMT:

1. All ___________ (solid, liquid & gas) is made up of tiny particles.

2. These particles are in constant _______________. This means they have kinetic
energy or “_______________” motion.

3. There are _____________ between the particles of matter.

4. The particles and spaces are so ______________ that they cannot be seen.

5. In a ____________, the particles are very close together, and the spaces between the
particles are small. Particles of a solid can not move very fast, but can only vibrate.

6. In a ____________, the particles are slightly farther apart, because the spaces
between the particles are larger. Liquid particles move slightly _________ than solid
particles.

7. In a ___________, the particles are very far apart. The spaces between the gas
particles are very large. Gas particles move very ____________.

8. If ______________ is added to matter, the particles gain kinetic energy, and so they
can move faster
The Kinetic Molecular Theory                               Name:____KEY________
                                                           Date:________ Per:___



____Kinetic____ means moving

____Molecules__ are particles of matter

____A Theory__ is used to explain observations

The kinetic molecular theory explains our observations of moving particles of matter

The KMT is a revised version of the particle model of matter. It explains the movement
(and not just the arrangement) of the particles in a solid, liquid or gas.

It explains what happens when heat is added to matter



There are eight statements in the KMT:

1. All ___matter________ (solid, liquid & gas) is made up of tiny particles.

2. These particles are in constant ___motion_________. This means they have kinetic
energy or “___moving_________” motion.

3. There are ______spaces_____ between the particles of matter.

4. The particles and spaces are so ____small____ that they cannot be seen.

5. In a ___solid_______, the particles are very close together, and the spaces between
the particles are small. Particles of a solid can not move very fast, but can only vibrate.

6. In a __liquid____, the particles are slightly farther apart, because the spaces between
the particles are larger. Liquid particles move slightly _faster______ than solid particles.

7. In a __gas_______, the particles are very far apart. The spaces between the gas
particles are very large. Gas particles move very __fast________.

8. If ___heat____ is added to matter, the particles gain kinetic energy, and so they can
move faster
POWER…(Chapter 7)

Power is the rate at fwhich energy is produced, absorbed or transferred.


POWER = ENERGY / TIME


(Energy – Joules, time - sec, Power – J/s = Watt)




o The power of an energy converter refers to how much work it can do in one second.


o The unit for measuring power is the watt.
         o   (1 watt = 1 joule/second)



Ex. In two minutes, an electric kettle transfers 144 000 J of energy to the water in it.
What is the power of the kettle?




Do the following conversions:

144 000J = __________kJ                       48 000 W = ___________ kW

120 kJ = __________ J                         4.2 J/s = ___________ W

1.2 kW = _________W                           8.4 x 103 W = __________kW
Power and Heat Worksheet                                  Name:_________________
                                                          Date:_________ Per:_____



1. What is the difference between thermal energy and heat?




2. Determine the power of each of the following electrical appliances.
      a) The output of a laser is 0.05J every 100 seconds.



      b) A curling iron uses 48000 J of energy per minute



      c) An electric light bulb uses 2.16 x 105 J of energy in one hour.



3. Determine the amount of energy transformed or used in each case
      a) A 2000 W electric pencil sharpener operates for 3.0 seconds



      b) A 1200 W kettle heats water for 5.0 seconds



      c) A 100 W stereo is operated for 1 hour.
Heat Capacity

   o The amount of heat required to change the temperature of an object.
   o It is an object’s “capacity” or “ability” to gain or lose heat

Eg. Apple pie filling – filling remains hotter than the crust.



Specific Heat Capacity

   o The amount of heat transferred when the temperature of 1.0kg of a substance
     changes (inc or dec) by 1.0o C
   o SHC is used to compare substances
   o Take equal masses of two materials, heat them up, and determine the rate at which
     the heat is transferred
   o This can be used to identify matter (See SHC chart on page 150)

How to calculate SHC:

SHC = Energy/(mass x change in temperature)


                E                     E=
                                      m=
SHC =       m x ∆T                    ∆T =
                                      SHC =




Sand vs. water at the beach…. (Pg. 150)

      Sand has _________ and water has ______________

      Sand holds heat for a _________ time water holds heat for a __________ time

      Sand takes a ________ time to heat up, water takes a _________ time to heat up
High Heat Capacity

       Different materials take different amounts of heat to raise a given mass of the
material the same temperature change. Water has a high SHC, and thus water can absorb
a large amount of energy. It takes a long time to heat up and a long time to cool down.



The SHC of Water:

4200 J/kg oC or 4.2 kJ/kg oC

This means it takes __________ J of energy to increase the temperature of _______ kg
of water by ________ o C

Or, if ______ kg of water was cooled by _______ oC, then it would release _________ J
of energy



Heat Transfer

Heat is a form of energy. It used to be thought that it was a type of matter called
“caloric” that flowed into cold objects. We now know that heat is ENERGY.

Law of Conservation of Energy

Energy can not be created or destroyed, it can only change form.




Do page 151 # 1-3
Changes of State




Draw a warming curve on the graph below (see pg 156). Make sure to fully label the
diagram




Define:
Latent heat -



Latent heat of fusion -



Latent heat of vaporization -