a car of mass 100kg starts from rest and attains the velocity of 10m/s in 5 second.Calculate the work done by normal reaction of the car?
 

Asked by somendra_nath | 11th Jan, 2016, 08:50: PM

Expert Answer:

The car of mass m is moving in the horizontal direction with acceleration a. 
However, the normal reaction acts on the car from the ground and in the vertical direction.
Now, we know that work done is given as dot product of force and displacement.
 
W = F · s = Fscosθ
Now, the angle between the displacement and the force of normal reaction is θ = 90°.
 
Therefore, work done is zero. W = Fscos90 = 0.

Answered by Romal Bhansali | 12th Jan, 2016, 12:16: PM