Motion: A Change in Position

1
Motion A Change in Position

• Presented by K. Whitfield
• 8.11.08
• Physical Science

2
All Motion is Relative

• Who is best to measure motion of a boat moving
  down the Trent River?
  
• The person riding the wake board behind the
  boat?
  
• The person riding a jet ski beside the boat?
• The person sitting behind the driver of the
  boat?
  
• The person sitting on a dock watching the boat go
  by?

3
More examples of relative motion

• Person walking on the bus
• In a car wash
• Sitting at a desk
• Motion is best measured by something stationary
  (not moving)

4
Types of Motion

• Uniform (not changing)
• Constant

5
Changing Motion

• Changing motion is acceleration (positive
  negative)

6
Linear Motion

• Object is moving in a straight line (linear)

7
Rotary Motion

• Object moves around an internal center of axis
• Spinning
• Examples top,merry-go-round,car tire,
  prop,tornado

8
Circular Motion

• Object moves around an internal axis
• Loop on a roller coaster

9
Scalars vs Vectors

• Scalars
• Quantities that can be fully described with
  amount and unit only
  
• Examples distance, speed, time, work, amp

10
Vectors

• Quantities that are fully described with amount,
  unit, and direction
  
• Examples displacement, velocity, acceleration,
  force

11
Distance vs. Displacement

• Distance amount and unit only (15 m)
• Displacement amount, unit, and distance (15 m to
  the left)
  
• Demonstration

12
Calculation Average Velocity and Speed

• Use the equation vd/t
• If d has a direction then you are finding average
  velocity and you must state direction from the
  displacement given
  
• Use the triangle
• Sample problems from handout