1. Acceleration

2. Acceleration is the rate of change of velocity.
Definition
Acceleration is the rate of change of velocity.

3. a = 9.8 m/s2
= 9.8 m/s/s
t (s)
v (m/s) 1 2 3 4 5 6 7 8 9 10
9.8
19.6
29.4
39.2
49.0
58.8
68.6
78.4
88.2
98.0

4. a = -9.8 m/s2
= -9.8 m/s/s
t (s)
v (m/s) 1 2 3 4 5 6 7 8 9 10
49.0
39.2
29.4
19.6
9.8 ? ? ? ? ?

5. Average Acceleration
a = vf - vi = Dv
tf - ti Dt
a Dt = vf - vi

6. Constant Acceleration
vf = vi + at

7. RECALL
RECALL
Velocity

8. v = ½ (vf + vi)
d = vit + ½ (vf - vi) t
= [vi + ½ (vf - vi)] t
= [vi + ½ vf - ½vi] t

9. = (½ vf + ½ vi) t
d = ½ (vf + vi) t

10. d = ½ ((vi + at) + vi) t = ½ (2 vi + at) t = ½ (2 vi)t + ½ (at) t
Constant Acceleration
Recall: vf = vi + at
d = ½ ((vi + at) + vi) t
= ½ (2 vi + at) t
= ½ (2 vi)t + ½ (at) t
d = vi t + ½ at2

11. vf - vi = at vf - vi = t a d = ½ (vf + vi) (vf - vi)
Recall: vf = vi + at & d = ½ (vf + vi) t
vf - vi = at
vf - vi = t a
d = ½ (vf + vi) (vf - vi)

12. 2ad = (vf + vi) (vf - vi) 2ad = vf 2 - vf vi + vf vi - vi 2

13. d a vf t
vf = vi + at
d = 1/2 (vf + vi)t
d = vit + 1/2at2
vf2 = vi2 + 2ad

14. Acceleration
Chart of Speed

15. Question
As a parachutist falls through the air, she falls faster and faster. Does her acceleration
A. Increase
B. Decrease
C. Remain the same

16. 0 s 0 m/s 1 s 1 m/s 2 s 3 m/s 3 s 6 m/ 4 s 10 m/s 5 s 15 m/s 0 m/s
Time Increasing
Acceleration
0 s 0 m/s
1 s 1 m/s
2 s 3 m/s
3 s 6 m/
4 s 10 m/s
5 s 15 m/s
Decreasing
Acceleration
0 m/s
10 m/s
19 m/s
27 m/s
34 m/s
40 m/s
Constant
Acceleration
0 m/s
10 m/s
20 m/s
30 m/s
40 m/s
50 m/s D1 D2 D3 D4 D5
D10 D9 D8 D7 D6
D10