Question

Calculate the work required to be done to stop a car of $1500kg$ moving at the velocity of $60km/h$?

Answer 1

When a object is moving with a constant velocity, it possess K.E

$K.E=\frac{1}{2}\times m\times v^2$

So, in order to bring the object to rest i.e its same magnitude of energy is required so, as the final final energy comes to zero.

$v=60km/hr=16.66m/s$

So, magnitude of work that needs to be done $=\frac{1}{2}\times m\times v^2$

Hence, work required to stop the car $=\frac{1}{2}\times 1500\times {16.66}^2$ $=208166.7J=208.17kJ$