Question

A body travelled at a velocity of 30m/s in a straight line and is brought to rest by the application of breaks if it covers a distance of 100m during this period.find the retardation

Answer 1

firstly we would calculate time distance divided by velocity that would be 10by 3second...then retardation is. negative acceleration so velocity multiplied by time with negative sign thts -100m per second square

Answer 2

By the third equation of motion:
${v}^{2} = {u}^{2} - 2rs$
0m/s^2=30m/s^2 - 2*r*100m
0=900-200r
0+200r=900
200r=900
r=900/200
r=9/2=4.5m/s^2