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Force and Motion

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					Force and Motion
Sir Isaac Newton (1642 - 1727)
                  His ideas are built upon
                   the ideas of Galileo.
                   Newton's three Laws of
                   Motion are general,
                   universal LAWS that
                   explain a wide range of
                   situations. (Newton also
                   invented Calculus and
                   made great contributions
                   in Optics, including
                   inventing the reflecting
                   telescope).
   Observe elephants and
    feathers, automobiles
    and skydivers to learn
    about the physics of
    air resistance, free-fall,
    inertia, and Newton's
    laws of motion.
Motion
   According to Newton's first law, an object in
    motion continues in motion with the same speed
    and in the same direction unless acted upon by an
    unbalanced force. It is the natural tendency of
    objects to keep on doing what they're doing. All
    objects resist changes in their state of motion. In
    the absence of an unbalanced force, an object in
    motion will maintain this state of motion. This is
    often called the law of inertia.
                    Force
   A force is a push or pull upon an object
    resulting from the object's interaction with
    another object. Whenever there is an
    interaction between two objects, there is a
    force acting on each of the objects. When
    the interaction ceases, the two objects no
    longer experience a force. Forces only
    exist as a result of an interaction.
                   Types of Forces
Contact Forces          Action-at-a-Distance Forces

Frictional Force        Gravitational Force

Tensional Force         Electrical Force

Normal Force            Magnetic Force

Air Resistance Force


Applied Force


Spring Force
   Speed - how fast
    an object is
    moving.“
   Velocity – speed in
    a given direction
   Acceleration - the
    rate at which an
    object changes its
    velocity
   Sports announcers will occasionally say that a
    person is accelerating if he/she is moving fast.
    Yet acceleration has nothing to do with going
    fast. A person can be moving very fast, and
    still not be accelerating. Acceleration has to do
    with changing how fast an object is moving. If
    an object is not changing its velocity, then the
    object is not accelerating.
   If the forces acting
    upon an object are
    balanced, then the
    object
   A is not moving.
   B. is moving with a
    constant velocity.
   C. both A and B.
   D. accelerating.
If the forces acting upon an object are
  balanced, then the object

   A is not moving.
   B. is moving with a constant velocity.
   C. both A and B.
   D. accelerating.
                         MASS
   The mass of an object (measured in kg) will be the same no
    matter where in the universe that object is located. Mass is
    never altered by location, the pull of gravity, speed or even
    the existent of other forces.
   For example, a 2-kg object will have a mass of 2 kg whether
    it is located on Earth, on the moon, or on Jupiter; its mass
    will be 2 kg whether it is moving or not and its mass will be
    2 kg whether it is being pushed or not.
                  WEIGHT
   On the other hand, the weight of an
    object will vary according to where in the
    universe the object is. Weight depends
    upon which planet is exerting the force
    and the distance the object is from the
    planet. Weight is equivalent to the force of
    gravity.
                          Falling
   Falling with Air
    Resistance
    As an object falls
    through air, it usually
    encounters some degree
    of air resistance. Air
    resistance is the result of
    collisions of the object's
    leading surface with air
    molecules.
   Suppose that an elephant and a feather
    are dropped off a very tall building from
    the same height at the same time.
    Suppose also that air resistance could be
    eliminated such that neither the elephant
    nor the feather would experience any air
    drag during the course of their fall. Which
    object - the elephant or the feather - will
    hit the ground first? The
 "Doesn'ta massive object
 accelerate at a greater rate
 than a less massive object?".
      Elephant and Feather - Air
             Resistance


     Suppose that an elephant and a feather
    are dropped off a very tall building from
    the same height at the same time. We will
    assume the realistic situation that both
    feather and elephant encounter air
    resistance. Which object - the elephant or
    the feather - will hit the ground first?
           Words to know!
 motion               unbalanced

 reference   point forces
 speed            average speed

 force            constant speed

 balanced forces  velocity

                   acceleration
The table and graph both present
  information about an object's
     position at certain times.
Time/s   Distance
         from
         start/m
0        0
2        20
4        40
6        60
8        80
Did we cover these
    objectives?
  What is the relationship
between force and motion?
  Why is it important to
understand the relationship
         between
    force and motion?
What mathematical skills can a
science student use to collect
     and analyze data?
   Identify and describe the
changes in position, direction of
motion, and speed of an object
  when acted upon by force.
Demonstrate that changes in
motion can be measured and
 graphically represented.
How can changes in motion
be measured and graphed?
  What do forces do to the
position, direction, or speed of
           an object?
               Works Cited
   http://www.math-
    science.sfasu.edu/physics101/Newton%27
    sLaws.html
   http://www.oldsci.eiu.edu/physics/DDavis/
    1350/05Laws/ToC.html
   http://www.physicsclassroom.com/mmedi
    a/newtlaws/cci.html

				
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posted:4/7/2013
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