A car moving with a speed of 54km/h is brought to rest within 10sec by applying break find the retardation due to breaks?
Initial speed of the car, u = 54 km/h = 54 × (5/18) m/s
=> u = 15 m/s
Final speed, v = 0
Time taken, t = 10 s
Using, v = u + at
=> a = (v - u)/t
=> a = (0 - 15)/10
=> a = -1.5 m/s2
The negative sign indicates that the acceleration is directed against the motion of the car. So, the retardation is 1.5 m/s2.