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Grade 10 Science (PowerPoint)


									    Grade 10 Science

Motion Unit
                  Significant Digits
   The correct way to record measurements is:
   Record all those digits that are certain plus one and no
   These “certain digits plus one” are called significant digits

       Table 1 Certainty of Measurements
Measurement                        Certainty
                            (#of Significant Digits)
  307.0 cm                             4
    61 m/s                             2
    0.03 m                             1
  0.5060 km                            4
3.00 x 10 8 m/s                        3
                                     2005     Decimal


A Red Arrow pops the 0’s             2500
like balloons until it sticks in
a digit between 1 and 9.
Then you count the rest of
the digits that are left.
         Counted and Exact Values

        When you count the number of something (example –
    students in the class), this is an exact value and has an
    infinite number of significant digits.
        When you use a defined value such as 100 cm/m or 60
    s/min, you also have an infinite number of significant
   Note the calculation rules on BLM 9.2B
                  Converting Units

   When you want to change                  100cm/m
    units we use a conversion
    factor (or equality)                     1000m/km
                                Equalities   60 s/min

                                             60 min/h
       Assignment : Significant Digits

   BLM 9.2a, 9.2b
   Complete the Significant Digits Worksheet See
    answer key
   Questions 1-6, 9 pg 349 in your text
    Relating Speed to Distance and Time

   Average Speed Vav is:
       The total distance divided by the total time for a trip
                      Vav =           d
                                      t
   See BLM 9.5a for examples
   Instantaneous speed – the speed an object is travelling at a
    particular instant. Ie. Radar trap
   Constant Speed (uniform motion) – if the instantaneous speed
    remains the same for a period of time. Ie. Cruise control on your car
A car travels 45 km at a speed of 90 km/h.
        How long did the trip take?
   What do you know in the Question
       d= 45 km
       Vav = 90 km/h
       t=?
   Decide on a formula
       t=    d
             Vav                d

                          Vav       t
     Substitute the knowns into the formula and solve
         t     = 45 km
                 90 km/h

              t = 0.5 h

•Write a concluding statement:

It takes 0.5 h for the car to travel 45 km at a speed of 90 km/h
          Problem Solving Summary

   List the variables you know
   Decide on a formula
   Substitute what you know into the formula
   Solve and write a concluding statement

                   Speed- Click Me
        Assignment : Relating Speed to
              Distance and time

   BLM 9.5 a,b, d
       Answer Key
   Questions 1,2,3,6,7,8 pg 358
   Answer Key
            Distance – Time Graphs

   Independent variable - X axis is always time
   Dependent Variable - Y axis is always distance
   Speed is determined from the slope of the best fit
    strait line of a distance – time graph
   SmartBoard Slope of a Line
             In the following diagram:
See BLM 9.7a A = constant speed
             B = not moving
             C = accelerating      Distance-Time Graphs
Assignment : Distance – Time Graphs
   Lab 9.5 Graphing Distances During Acceleration
   Questions 3,4,5,6 pg 365
       Answer Key
   Activity 9.9 Simulation : Average Speed on an Air Table
       BLM 9.9a
   Worksheet – Determining Speed from a d/t Graph
       Q 1-6
            Answer Key
   Lab9.6 Balloon Cars Lab
   Lab 9.10 Determining an Average Speed
   Review Questions 1,3,4,7,9,11 pg 376
       Answer Key
   Test Chapter 9
Chapter 11 Displacement and
               Introduction to Vectors

   Reference Point – origin or starting point of a journey. Ie. “YOU ARE
    HERE” on a mall map

   Position – separation and direction from a reference point. ie. “150 m
    [N] of “YOU ARE HERE”

   Vector Quantity – includes a direction such as position. A vector
    quantity has both size and direction ie. 150m [N]

   Scalar quantity – includes size but no direction. ie. 150 m
                     Symbol           Example
Quantity Symbol

                  Scalar Quantity

   Distance                            292 km
     Time                               3.0 h
                  Vector quantity
                                    2 km [E] (from
                        d               Subway)

                            d          292 km [S]
   Displacement – a change in position.
   See BLM 11.1a
   Symbol Format – used when communicating a
   See BLM 11.1b
   Drawing Vectors –
       state the direction (N,E,S,W)
       Draw the line to the stated scale or write the size of the
        vector next to the line
       The direction of the line represents the direction of the
        vector and the length of the line represents the size of
        the vector
     Assignment : Introduction to Vectors

   Questions 1,5,6,7,8 pg 417
   Walk the Graph Activity pg 418 & BLM 11.2
     Adding Vectors on a Straight Line
   Vector Diagrams – Join each vector by connecting
    the “head” end of one vector to the “tail end of the
    next vector.

   Find the resultant vector by drawing an arrow from
    the tail of the first vector to the head of the last
    Resultant displacement -           dR
    is a single displacement that has the same effect as
        all of the individual displacements combined.
Adding vectors can be done by one of
     the following methods

usingscale diagrams
adding vectors algebraically

combined method

 See   BLM 11.3
     11.3 Adding Vectors Along a Straight Line

Two vectors can be added together to determine the
          (or resultant displacement).

           Use the “head to tail” rule
Join each vector by connecting the “head” and of a
                    vector to the
           “tail” end of the next vector

          Resultant vector
              Scale Diagram Method

Leah takes her dog, Zak, for a walk. They walk 250 m
[W] and then back 215 m [E] before stopping to talk to a
neighbor. Draw a vector diagram to find their resultant
displacement at this point.
Scale Diagram Method

1)State the direction (e.g. with a compass symbol)

2)List the givens and indicate the variable being solved
 d1 = 250m [W], d2 = 215m [E], dR = ?
3)State the scale to be used
      1 cm = 50 m
4)Draw one of the initial vectors to scale
5)Join the second and additional vectors head to tail and
to scale

6)Draw and label the resultant vector

7)Measure the resultant vector and convert the length
using your scale
        0.70 cm x 50m / 1 cm = 35m [W]

8)Write a statement including both size and direction of
the resultant vector
The resultant displacement for Leah and Zak
Is 35 m [W].
            Adding Vectors Algebraically

This time Leah’s brother, Aubrey, takes Zak for a walk
They leave home and walk 250 m [W] and then back
175 m [E] before stopping to talk to a friend. What is the
resultant displacement at this position.
Adding Vectors Algebraically
When you add vectors, assign + or – direction to the value
of the quantity.
             (+) will be the initial direction
             (-) will be the reverse direction

1.Indicate which direction is + or –
           250 m [W] will be positive
2.List the givens and indicate which variable is being

       d1 = 250 m [W], d2 = 175 m [E], dR = ?
        3.Write the equation for adding vectors

                    dR =      d1 +    d2

        4.Substitute numbers (with correct signs) into the
        equation and solve
         dR = (+ 250 m) + (-175 m)
         dR = + 75 m or 75 m[W]
        5.Write a statement with your answer ( include
        size and direction)
The resultant displacement for Aubrey and Zak is 75 m [W]
                               Combined Method

Zak decides to take himself
for a walk.

He heads 30 m [W] stops,
then goes a farther 50 m [W]
before returning 60 m[E].

What is Zak’s resultant
Combined Method

1)State which direction is positive and which is negative

     West is positive, East is negative

2)Sketch a labeled vector diagram – not to scale but
using relative sizes
                50m              30m

                 60m                  dR
3)Write the equation for adding the vectors

               dR = d1 +d2 +d3

4)Substitute numbers( with correct signs) into the equation and
        dR = (+ 30 m) + (+50m) + (-60m)
        dR = + 20m or 20m [W]

5)Write a statement with your answer (including size and

  The resultant displacement for Zack is 20 m [W]
Assignment : Adding Vectors in a Straight

   Questions 1-3,5-7 pg 423 Answer Key
   Activity “Bug Race”
          Adding Vectors at an Angle

      If we know the path an object takes we can draw an
    accurate to scale vector diagram of the journey. We can
    then determine the following;
   compare the final position to the reference point
   determine the resultant displacement
   Certain rules must be followed add vectors at an angle.
    See BLM 11.5a
     Adding Vectors at an Angle

                               Scale 1 cm = 5 Km

                   d R = 5cm
                               dR = 5 cm x 5 Km/1cm
d 1 = 3 cm
                               dR = 25 Km [NW]

               d 2 = 4 cm
    Assignment : Adding Vectors at an Angle

   BLM 11.5b
   Activity “Hide a Penny Treasure Hunt”

        Velocity –       v
       a vector quantity that includes a direction and a speed
        ie. 100 km/h [E]

   Constant Velocity – means that both the size
    (speed) and direction stay the same
   Average Velocity – v      av
        is the overall change of position from the start to finish.
        It is calculated by dividing the resultant displacement
        (which is the change of position) by the total time
       V av      =       dR
   See BLM 11.7a,b
              Assignment : Velocity

   BLM 11.7c
   Questions 3,5,7, pg 436
   Activity Tracking and Position pg 438 & BLM 11.9
   Review Questions 4,8,9,10 pg 442
   Test Chapter 11
Chapter 12 Displacement, Velocity,
         and Acceleration
           Position – Time Graphs

       Position and displacement are vectors and
    include direction. It is possible to represent vector
    motion on a graph. Very much like a distance –
    time graph. Can you see the differences?
Can you see the differences?
   The slope of a position-time graph is equal to the
    velocity of the motion

   The slope of the tangent at a point on a position-
    time graph yields the instantaneous velocity.

   Instantaneous velocity is the change of position
    over an extremely short period of time.
    Instantaneous velocity is like instantaneous speed
    plus a direction
       Assignment : Position-Time Graphs

   Activity : Describing Position-Time Graphs “Walk
    the Dog”
   Activity : The Helicopter Challenge
   Exercise : BLM 12.1 a,b,c
Velocity Time Graphs
   A velocity – time graph can show travel in opposite
    directions over a period of time.

   The slope of the line on a velocity –time graph
    indicates the acceleration of an object
   Acceleration – a
    is calculated by dividing the change in velocity by
    the time. Because there is a direction associated
    with the velocity, the acceleration is also a vector

   Constant acceleration is uniformly changing

a   =     v

   Average Velocity of an object in motion can be
    determined from the ratio of total distance divided
    by total elapsed time.
                  V av   =        dR

                   See BLM 12.2 a,b
     Assignment : Velocity – Time Graphs

   BLM 12.2 c
       Acceleration and Displacement

   Acceleration is the change of velocity over time
   Questions 5,7,8 pg 465
   Test Chapter 12

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