Motion Physics

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Motion Physics

• 8th Grade Science

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Frame of Reference

• An object is in motion when its distance from
  another object is changing. Whether an object is
  moving or not depends on your point of view. For
  example, a woman riding on a bus is not moving in
  relation to the seat she is sitting on, but she
  is moving in relation to the buildings the bus
  passes. A reference point is a place or object
  used for comparison to determine if something is
  in motion. An object is in motion if it changes
  position relative to a reference point. You
  assume that the reference point is stationary, or
  not moving.

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Frame of Reference
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Speed

• If you know the distance an object travels in a
  certain amount of time, you can calculate the
  speed of the object. The speed of an object is
  the distance the object travels in one unit of
  time. To calculate the speed of an object, divide
  the distance the object travels by the amount of
  time it takes to travel that distance.

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Speed
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Average Speed

• When an object travels at a constant speed, its
  speed at any moment during its motion is the same
  as it is at every other moment. Most objects do
  not move at constant speeds. To find the average
  speed of an object, divide the total distance
  traveled by the total time

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Instantaneous Speed

• An objects instantaneous speed is the rate it is
  moving at a given instant. An objects speed
  tells how fast it is moving, but not the
  direction of the motion

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Velocity

• When you know both the speed and direction of an
  objects motion, you know the velocity of the
• object. Speed in a given direction is called
  velocity.

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Acceleration

• Acceleration is the rate of change in the
  velocity of an object. Velocity can change in
  three different ways. Speed up, slow down, or
  changing direction. All three of these changes
  are technically called acceleration.

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Acceleration

• Final Velocity original velocity
• Time

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Acceleration

• The slowing down of an object can be referred to
  as deceleration and the changing of direction can
  be called circular motion.

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Momentum

• Determines how difficult it is to start or stop
  an objects motion.
• All moving objects have momentum.
• Momentum depends on the mass of the object and
  the velocity with which it is traveling.

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Momentum

• The formula for momentum is
• Mass x Velocity

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Conservation of Momentum

• The total momentum of any group of objects
  remains the same unless outside forces act on the
  objects.
• This means that momentum is conserved. If one
  object loses momentum, but another must gain what
  is lost.

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Conservation of Momentum

• E.g.
• Billiards- The momentum from the moving ball is
  transferred to the stationary balls. None of the
  momentum is lost. It is transferred from the cue
  ball to the rack.