Question

A car starting from rest accelerates for 15 min. until its velocity is 20 m/s. It then moves at a constant velocity from another 20 min. before it slows down and finally stopped in another 10 m. Find the acceleration during the first 15 min.

Answer 1

Given:

$v_0=0,$

$t_1=15\:\rm min=900\: s$

$v_1=20\:\rm m/s$

The acceleration during the first 15 min

$$a=\frac{\Delta v}{\Delta t}=\frac{v_1-v_0}{t_1}$$

$$a=\frac{20\:\rm m/s-0\: m/s}{900\:\rm s}=0.022\:\rm m/s^2$$