Question

A bus moving with a velocity of 60 km/h is brought to rest in 20 sec by applying the brake, find acceleration.

Answer 1

Given,
Initial velocity, u = 60km/h = 60 x (5/18) = 50/3 m/s
Time, t= 20 sec
Final velocity, v = 0

Using the first equation of motion,
v = u + at
0 = (50/3) + a.20
a=-(50/3)/20
a= -5/6 = -0.83 $m/s^2$.
Note: negative sign shows retardation.