Question

A car travelling at 36 km/hr speeds up to 72 km/hr in 5 sec, what is its acceleration? If the same car stops in 20 sec, what is its retardation?

Answer 1

For first case,

u=36km/hr

v=72km/hr

t=5s

a=?

So, a=v-u/t

=72-36/5

=7.2m/s^2

For case 2,

u=72km/hr

v=0

t=20s

retardation=a=?

So, a=v-u/t

=0-72/20

=-3.6m/s^2