Question

Steve is in a car sitting at a stop light. When the light changes he accelerates west until he reaches a speed of 40m/s, which takes 12 seconds. a) What is the acceleration? b) How far did the car travel while accelerating?

Answer 1

Given:

$v_i=0\:\rm m/s;$

$v_f=40\:\rm m/s;$

$t=12\:\rm s.$

(a) The acceleration

$$a=\frac{v_f-v_i}{t}=\frac{40-0}{12}=3.3\:\rm m/s^2.$$

(b) Distance

$$d=\frac{v_f+v_i}{2}t=\frac{40+0}{2}\times 12=240\:\rm m.$$