Calculate the amount of work needed to stop a car of 500 kg, moving at a speed of 36 km/h.
Given
Mass of car = 500 Kg
Initial speed = 36 km/h = 10m/s
(∵ 1 km/h = 5/18 m/s)
Now
Work done = Change in Kinetic Energy.
= Final kinetic Energy – Initial Kinetic Energy.
= 
=
(Final velocity = 0, because the car is at rest).
= 
.
The magnitude of work required is 25000 Joule.
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