1. Chapter 5 Matter In Motion
Section 1 – Measuring Motion pp

2. Reference Point
Reference point – an object that appears to stay in place.
Stationary reference points (examples) buildings, trees and mountains.
Moving reference points (examples) birds and the earth in relation to the sun.

3. Motion
Motion – an object is in motion when it changes in position over time when compared with a reference point. You can describe the direction of its motion with a reference direction (such as north, south, east, west, up, down)

4. Speed
Speed – the rate at which an object moves. Speed depends on distance traveled and the time taken to travel that distance.

5. Speed = s=d t s=speed (meters/second) d=distance (meters)
t=time (seconds)
Average Speed equals the total distance divided by the total time.
average speed =
total distance
total time

6. CALCULATING AVERAGE SPEED
Complete Math Focus
Problems on p. 120.

7. Velocity: Direction Matters
The speed of an object in a particular direction is called velocity.
Speed and velocity are two different terms with two different meanings. Velocity must include a reference direction.
v=d t
v=velocity
d=distance
t=time
Examples:
25m/s northwest
25m/s down the hall

8. Velocity: Direction Matters
Changing Velocity You can think of velocity as the rate of change of an object’s position. An object’s velocity is constant only if its speed and direction don’t change.

9. Chapter 5
Calculating Resultant Velocity Measuring Motion

10. POSITION – TIME GRAPHS

11. Acceleration
Is the rate of change of the velocity(how quickly an object changes its velocity)
The faster velocity changes the greater the acceleration is.
The change of velocity divided by the change of time.

12. Acceleration a=Vf - Vi t
Acceleration= final velocity – starting velocity
time it takes to change velocity

13. Acceleration a = acceleration vf = final velocity
vi = initial velocity or starting velocity
t = the time it takes to go from the initial velocity to the final velocity

14. Examples of Units for Acceleration
Acceleration can be expressed in meters per second per second ( m/s/s)
Or meters per second squared(m/s2)
Or Km/min/sec
Or m/min/hr

15. 3 Methods of Acceleration
Speeding up (accelerating)
Slowing down (decelerating)
Turning (changing direction)

16. IMPORTANT DEFINITIONS
Centripetal acceleration – the acceleration that occurs in circular motion.

17. Recognizing Acceleration on a Graph – See “A Graph Showing Acceleration” on p. 122