1. Chapter 10 Section 2 Pages 325 - 330
Acceleration
Chapter 10 Section 2
Pages 34

2. Objectives
Describe the concept of acceleration as a change in velocity.
Explain why circular motion is continuous acceleration even if the speed doesn’t change. 34

3. Acceleration--the rate at which velocity changes
Units-- m/s2 35

4. Remember that velocity includes speed and direction so you can change your acceleration by a change in speed, direction or both 35

5. What three controls in a car could cause it to accelerate?

6. Speed up
0 to 100 m/s 36

7. Slow down—negative acceleration36

8. Also called . . . 36

9. Direction
Acceleration can also be a change in direction

10. Centripetal Acceleration
Uniform circular motion is constant acceleration
No change in speed, only a change in direction 37

11. Acceleration equation
Acceleration = final velocity – initial velocity
time
A =v t
 Means change 38

12. Acceleration equation
Acceleration = final velocity – initial velocity
time
 Means change
A =v t
Sports car can go from 0 to 96km/h in 3.7s
96-0km/h =7.2m/s2
3.7s
Note the answer is in m/s2 38

13. Vf-vi a t

14. Different forms of the equation
vf - vi = at to solve for speed or velocity
t = vf - vi to solve for time a

15. Velocity time graph The slope of the line gives you acceleration
A straight line indicates constant acceleration
Veloci ty
time

16. time What does this line indicate???
The slope is zero because the acceleration is zero
Veloci ty
time

17. Film

18. Assignment Correction on problem 4:
Marisa’s car accelerates at an average rate of 2.6 m/s2. Calculate how long it takes her car to speed up from 24.6 to 26.8m/s.
If the class has done well, you may work in groups. Otherwise it may be done individually.

19. Freefall -- an object falling free of all restraint

20. The Gravitational Constant
Acceleration due to gravity
is 9.8m/s2

21. Acceleration due to gravity
V=at
Velocity = acceleration times the time
a– acceleration
t – time
Acceleration due to gravity
is 9.8m/s2

22. How fast? v=at Remember gravity is 10m/s2
Time in seconds
seconds 1 2 3 4 5 6 7 8 ms

23. Distance of Fall
Time in seconds 1 2 3 4 5 6 7 8
D=1/2at2

24. Distance of Fall
D=1/2at2

25. Your Assignment
Side 1
A ball is dropped with a speedometer and odometer attached
Fill in the speedometer and odometer readings for each second of fall
Use v=at and d=1/2at2

26. Part one read and answer
Side 2
Part one read and answer
Part two use s=d/t and rearrangements to solve the problems
Part three—this time the acceleration is not due to gravity (not freefall)
use the same two equations you know v=at and d=1/2at2
Note that the acceleration is different

27. Part 2 d s t d = st s s To get t by itself divide both sides by s
s=d/t
To get d by itself, multiply both sides by t
St=dt d=st t
To get t by itself divide both sides by s
d = st
s s

28. Freefall Two equations v=at and d=1/2at2 speedometer—shows how fast
odometer—shows how far
Two equations
v=at and d=1/2at2

29. Freefall Two equations v=at d=1/2at2 speedometer—shows how fast
odometer—shows how far
Two equations
v=at
d=1/2at2

30. Freefall assignment d= how fast? d=1/2at2 0s 1s 2s 3s 4s 5s
v= how fast v=at

31. Freefall -- an object falling free of all restraint

32. Acceleration due to gravity
V=at
Velocity = acceleration times the time
a– acceleration
t – time
Acceleration due to gravity
is 9.8m/s2

33. How fast? v=at 0s 1s 2s 3s 4s 5s 6s 7s 8s

34. Distance of Fall
D=1/2at2 1 2 3 4 5 6 7 8

35. Freefall Two equations v=at and d=1/2at2 speedometer—shows how fast
odometer—shows how far
Two equations
v=at and d=1/2at2