A car of mass 1200 kg is brought to rest from a speed of 20 ms^-1 by a constant braking force 3000 N. calculate the retardation and the time the car takes to come to rest. (Force F=3000N, since force applied is to bring the car to rest).

Answer 1

a = f / m = 3000 N / 1200 kg = 2.5 m/s^2

t = v / a = 20 m/s / 2.5 m/s^2 = 8 s