Question

A car accelerates from $36km/h$ to $90km/h$ in $5s$ on a straight road. What was its acceleration in $m/s^2$ and how far did it travel in this time? Assume constant acceleration and direction of motion remains constant.

Answer 1

$u=36\times \frac{5}{18}=10m/s$

$v=90\times \frac{5}{18}=25m/s$

$t=5s$

$v=u+at$

$25=10+a\times 5$

$15=5a$

$a=3m/s^2$

$s=ut+\frac{1}{2}a{t}^2$

$=10\times 5+\frac{1}{2}\times 3\times 25$

$=50+\frac{75}{2}$

$s=\frac{100+75}{2}=\frac{175}{2}=87.5m$

$a=3m/s^2$