AP Physics 1

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

b) Constant Velocity

1. Equation

a = ∆V/∆t = (V_f - V_i)/t

Ex 1

Starting Velocity: 80 km/h West

Final Velocity: 110 km/h West

Acceleration: 1.6 m/s²

How long did it accelerate?

(V_f - V_i) = 30 km/h W

Convert to m/s²

30 km/hrx[1000m/km]x[1 h/3600 sec]

= 8 m/s

a = (V_f - V_i)/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)

Motion Equations}