These questions consists of two statements each printed as Assertion and Reason. While answering these question you are required to choose any one of the following five reponses
(a) If both Assertion and Reason arecorrect and Reason is the correct explanation of Asserrtion.
(b) If both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
(c ) If Assertion is true but Reason is false.
(d) If Assertion is false but Reason is true.
Assertion If the surface between the blocks A and B is rough, then work done by friction on block B is always negative.

Reason Total work done by friction in both the blocks is always zero.

Answer

C

Explanation

(c ) Work done by friction on A is positive and on B is negative. If there is no slipping between the two blocks then `s_(A)=s_(B)`. Therefore net work done will be zero, otherwise not.