1. Speed and Acceleration

2. Motion
Motion occurs when an object changes position relative to a reference point
You do not need to see an object in motion in order to know that movement has taken place

3. Time A particular moment Interval of time
Measured in years, days, hours, minutes, and seconds
Remember – science measures in seconds
Always a number and a unit s

4. Distance How far from one point to another Unit of length
English and metric
Remember – metric only in science
Always a number and a unit m

5. Displacement
Displacement is the distance and direction of an object's change in position from the starting point
Displacement is different than distance if an object changes direction during its motion

6. Speed Speed is the distance an object travels per unit of time.
Measure of how quickly an object moves from one place to another
An object that is not moving still has a speed---zero (0 m/s)
S = d t

7. Speed
s = d t
s = speed
d = distance
t = time

8. Average Speed Total distance traveled total time traveling
Speed does not have to be constant
90m/30 min = 30 m/m
90m/90min = 1 m/m

9. Instantaneous speed Speed at a certain moment in time
A speedometer shows how fast a car is going at one point in time or at one instant.

10. Changing instantaneous speed
When something is speeding up or slowing down, its instantaneous speed is changing.
If an object is moving with constant speed, the instantaneous speed doesn't change

11. Changing speed Speed is usually not constant
Picture riding a bike or going out for a walk

12. Velocity Velocity is speed of an object plus its direction
EX - a car is traveling 65 mi/hr north
Velocity = v
Therefore v = d t

13. Velocity
Velocity depends on direction as well as speed so the velocity of an object can change even if the speed of the object remains constant
The speed of this car might be constant, but its velocity is not because the direction of the car is always changing.

14. Graphing Speed A speed graph is always position vs time
Position (or distance) is on the y axis
Time is on the x axis
The slope of a position time graph is speed

15. What is the speed?

16. Acceleration
Section 2.2

17. Acceleration, Speed and Velocity
Acceleration is the rate of change in velocity
When the speed OR direction of an object changes, the object is accelerating
Acceleration can be positive or negative
If an object is slowing down, it is negative
If an object is speeding up, it is positive

18. Changing Direction
An object’s speed does not have to change for it to accelerate
An object is accelerating if it’s direction changes as well

19. Calculating Acceleration
A= Vf –Vi/t
Acceleration equals final velocity-initial velocity divided by time
Vf-Vi is also called change in velocity

20. Negative Acceleration
Description
Graph
Happens when an object slows down
Final velocity is less than the initial
Example: A car brakes from 30 mph to a stop
Change in speed= 0mph-30mph = -30 mph

21. Positive Acceleration
Description
Graph
Happens when an object speeds up
Final velocity is more than the initial
Example: A car accelerates from 0 mph to 60 mph
Change in speed= 60 mph-0mph= 60 mph

22. No Acceleration Description Graph Velocity is not changing
Speed and direction are constant