Question

A car travelling at 36km/hr to 72km/hr in5 sec .what is the acceleration ?If the same stops in 20sec ,what is it retardation

Answer 1

a=v2-v1\2
=20-10/2
a=5ms-2

Answer 2

first we'll convert km/hr into m/s

36 × 5/18 = 10m/s
72 × 5/18 = 20m/s

u(initial velocity) = 10m/s
v(final velocity) = 20m/s
t = 5 sec

acceleration = v-u/t
=20-10/5
= 2m/s^2

retardation.....

u(initial velocity) = 20m/s
v(final velocity) = 0m/s
t = 20
retardation = v-u/t
= 0 - 20/20
= -1m/s^2