Question

How much work is required to be done to stop an object of 150 Kg moving with a velocity of 72 km/hr?
150J
1500J
300J
3000J​

Answer 1

Answer:

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

K.E=21×m×v2

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 =21×m×v2

Hence, work required to stop the car =21×1500×16.662 =208166.7J=208.17kJ