The kinetic energy of a vehicle of mass 1000 kg is 45 105 J

The kinetic energy of a vehicle of mass 1000 kg is 4.5 × 10⁵ J. It is braked with a total constant braking force of 6000N. What will be its stopping distance?

A 37m

B 75m

C 150m

D 300m

Solution

Mass = 1000 Kg, Stopping Force = 6000 N, So acceleration a = - (6000/1000) m/sec² = - 6 m/sec². ( -ve sign because force is in opposite direction of motion).

So finally body is stopped so V=0 and from given Kinetic Energy (1/2 X 1000 X u²) = 4.5 x 10⁵ J , we get U = 30 m/sec. Now from

V² - U² = 2xaxS , we get Stopping distance S = 75 m.