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AP Physics 1
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Distance and Motion
St. Mary's HS
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C.
Acceleration - time rate
of change in velocity
(how quickly velocity is changing)
Which car has the greater acceleration?
t(sec) |
t = 0 |
t = 1 |
t = 2 |
t = 3 |
t = 4 |
t = 5 |
Car A |
70 m/s |
72 m/s |
74 m/s |
76 m/s |
78 m/s |
80 m/s |
Car B |
0 m/s |
3 m/s |
6 m/s |
9 m/s |
12 m/s |
15 m/s |
Car C |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
Car D |
100 m/s |
99 m/s |
98 m/s |
97 m/s |
96 m/s |
95 m/s |
Car A
+2 m/s/s
Car B
+3 m/s/s
Car C
0 m/s/s
Car D
- 1 m/s/s
t(sec) |
t = 0 |
t = 1 |
t = 2 |
t = 3 |
t = 4 |
t = 5 |
Car A |
70 m/s |
72 m/s |
74 m/s |
76 m/s |
78 m/s |
80 m/s |
Car B |
0 m/s |
3 m/s |
6 m/s |
9 m/s |
12 m/s |
15 m/s |
Car C |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
90 m/s |
Car D |
100 m/s |
99 m/s |
98 m/s |
97 m/s |
96 m/s |
95 m/s |
2 Ways to Have
Zero Acceleration
a) Remain at Rest ![](eskimo_ice_skating_lg_wht.gif)
b) Constant Velocity
![](big_boy_skateboarding_lg_wht.gif)
1. Equation
a =
∆V/∆t
= (Vf
- Vi)/t
Ex 1
![](action_hero_williams_chased_helicopter_lg_wht.gif)
Starting Velocity: 80 km/h West
Final Velocity: 110 km/h West
Acceleration:
1.6 m/s2
How long did it accelerate?
(Vf
- Vi) = 30 km/h W
Convert to
m/s2
30 km/hrx[1000m/km]x[1
h/3600 sec]
= 8 m/s
a =
(Vf
- Vi)/t
1.6 m/s2 = (8 m/s)/t
t = 5 sec
An object has an
acceleration of
-12 m/s2
Is it accelerating or decelerating?
Depends ....
If velocity is negative,
accelerating
ex)
-100 m/s to -124 m/s in 2 sec
If velocity is +,
decelerating
124 m/s to 100 m/s in 2 sec
Acceleration
V +, A+
V-, A-
Deceleration
V+, A-
V-, A+ |
'Accelerating Backwards'
(Because the force required to slow an object
always opposes
the objects motion)
![](../../HR/smmetrose.gif)
Motion Equations ![](quon_hold_on_fast_scooter_md_wht.gif)
![](../../HR/smmetrose.gif)
ŠTony
Mangiacapre.,
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