Motion involves a change in position over time relative to a reference point. Speed is the distance an object moves in a given time. Velocity includes both speed and direction of motion. Acceleration is a change in velocity over time, such as speeding up, slowing down, or changing direction. Examples of acceleration include a car stopping or speeding up, while moving at a constant speed around a track is not an acceleration. The acceleration formula is the change in velocity divided by time.

1. Motion Notes
Speed, Velocity, and Acceleration!

2. Motion
 A change in position, over time, relative to
a reference point.

3. So, What’s a Reference Point?
 http://www.classzone.com/books/ml_scie
nce_share/vis_sim/mfm05_pg7_relmotio
n/mfm05_pg7_relmotion.html
 What we compare all other movement or
locations to!
 Often Earth Features
 Large Objects
 Cities

4. Reference Point Scenarios
Suppose you are in a train, and you cannot tell if you are
stopped or moving. Outside the window, another train is
slowly moving forward. What could be happening?
 Your train is stopped, and the other train is moving slowly
forward…
 The other train is stopped, and your train is moving slowly
backwards…
 Both trains are moving forward, with the other train moving a
little faster…
 Your train is moving very slowly backward, and the other train
is moving slowly forward…
Could you be sure as to which is actually happening??

5. Reference Point Examples

7. Speed
 Position can change at different rates
 Distance an object moves in an amount
of time
 Formulas
 Speed=Distance/Time
 Distance=Speed x Time
 Time= Distance/speed

8. Suppose there’s a TORNADO that’s 1 mile
wide, and it’s going 40 mph…
What else is important?!?!?
It’s Direction!
Velocity is a Speed in a Direction!
15 Mph Northwest; 200 m/s South;
40 cm/ms Left
Velocity

9. Acceleration
 Change in Velocity over time
 Remember: Velocity is Speed AND Direction
 “Speeding Up” = Acceleration (Positive #)
 “Slowing Down” = Deceleration (Negative #)
 Turning (Change in Direction) = Acceleration

10. Which of the Following Are
Examples of Acceleration?
A car stops at a stop light.
A car goes from 0 to 45
mph.
A car races around an oval
track at a constant speed.

11. Acceleration Formula
THIS IS TOUGH!!!
Final Velocity – Initial Velocity
Time
Vfinal– Vinitial
T

12. Acceleration Problem!
Julio starts sliding with a velocity of 1m/s south. After 3 seconds, his
velocity is 7m/s south. What is Julio’s acceleration?
Final Velocity – Initial Velocity
Time
7 m/s – 1 m/s
3s
6 m/s
3s
2 m/s
s
2 m/s2

13. Practice!
Review:
Speed/Distance/Time Formulas:
S=D÷T D=T·S T=D÷S
Acceleration Formula:
Final Velocity – Initial Velocity
Time

14. Practice
If a runner runs 100 meters in
50 seconds, what is his
speed in meters per second?
How far could this runner run
in 25 seconds?

15. Calculating Acceleration
John starts running from
rest. After 10 s, his velocity is
20 m/s. What is John’s rate
of acceleration?