1. Motion

2. Describing Motion
Motion – when an object changes its position relative to a reference point
Distance – how far an object moves
Displacement – how far an object moves in reference to the starting point

3. Rates Any change over time Examples: $7.50/hr
Rpm (rotations per minute)
Accidents/month
Miles/hr
m/s

4. Speed / Velocity Distance traveled per unit of time
Speed = distance / time
Speed describes the rate of motion
Velocity includes the rate of motion and direction

5. Speed Speed that doesn’t change over time is constant speed
Most speeds are non constant average speed
Why can’t you run at a constant rate?

6. Average and Instantaneous Speed
Average speed is taken when speed is variable.
Average speed = total distance / total time
Instantaneous Speed = speed at any given point in time

7. Distance vs. Time Graphs
What does this graph represent?
Visual representation of an object’s motion
Plot distance on the vertical axis (y-axis)
Plot time on the horizontal axis (x-axis)
Which is the independent variable?
Which is the dependent variable?

8. AGENDA 1/19/11 You will need your textbook for the assignment today
Access Chapter 2 Notes from my public folder
Acceleration Discussion
Ch. 2 Handout

9. YOU CAN FEEL ACCELERATION
Acceleration is a change in the motion of an object.
Positive acceleration – velocity is increasing
Negative acceleration – velocity is decreasing
Changing an object’s direction is also accelerating
YOU CAN FEEL ACCELERATION

10. Calculating Acceleration
Acceleration = change in velocity / time
A = ΔV / t
(VF – VI)
___________ t

11. Acceleration Unit of acceleration is m/s2. A velocity vs. time graph
Which is the dependent variable?
Which is the independent variable?

12. (+) acceleration has a positive slope
(-) acceleration has a negative slope

13. Where is acceleration experienced at an
Amusement Park?

14. Newton’s Laws of Motion
1st Law- “an object in constant motion remains in constant motion until acted upon by an outside force.”
The law of inertia
2nd Law- F = ma
3rd Law- “for every action there is an equal and opposite reaction.”

15. Forces Force- a push or a pull exerted from one object to another
Balanced Forces- forces acting on an object are all equal and in opposite directions
Unbalanced Forces- the magnitude and direction of the forces do not cancel one another out
Causes motion