question_answer

A block of mass M is kept on a platform which is accelerated upward with a constant acceleration 'a' during the time interval T. The work done by normal reaction between the block and platform is

A) \[-\frac{Mga{{T}^{2}}}{2}\]                

B) \[\frac{1}{2}M(g+a)a{{T}^{2}}\]

C) \[\frac{1}{2}M{{a}^{2}}T\]

D) Zero

Correct Answer: B

Solution :

     Work done by normal reaction \[=Nh=M(g+a)\frac{1}{2}a{{T}^{2}}=\frac{1}{2}M(g+a)a{{T}^{2}}\]