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A block of mass m is kept on a rough hor...

A block of mass m is kept on a rough horizontal surface. It is moved through a distance (s) by applyig a force F in the horizontal direction. What is the work done by the normal reaction?

A

`Rxxs`

B

zero

C

`-Rxxs`

D

`(Rs)/2`

Text Solution

Verified by Experts

The correct Answer is:
B
In the first case, the centre of gravity is at a height `=b/2`
`therefore "Work done=mgh=mg"(b/2)`
In the second case, the height of the centre of gravity `=L/2`
`therefore" Work done "=mg L/2 therefore L gt b`
`therefore" Extra work done "=mg ((L-b)/(2))`
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