Question

A block of mass 10kg is released on a fixed wedge inside a cart which is moved with constant velocity 10m/s towards right. Take initial velocity of block with respect to cart zero. Then work done by normal reaction (with respect to ground )on block in two seconds will be: (g = 10m/s²).

(A) zero 

(B) 960 J 

(C) 1200 J 

(D) none of these

Answer 1

Correct option (B) 960J

Explanation:

Because the acceleration of wedge is zero, the normal reaction exerted by wedge on block is 

N = mg cos37° . 

The acceleration of the block is g sin 37° along the incline and initial velocity of the block is v = 10 m/s horizontally towards right as shown in figure.