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A cord is used to lower vertically a blo...

A cord is used to lower vertically a block of mass M through a distance `d` at a constant acceleration `g//4`. Find the work done by the cord on the block.

A

`Mgd/4`

B

`3Mgd/4`

C

`-3Mgd/4`

D

`Mgd`

Text Solution

Verified by Experts

The correct Answer is:
`(3)`
When the block moves vertically downward with acceleration `g/4` then tension in the cord
` T = M(g - (g)/4) = 3/4 Mg`
Work done by the cord =` F.s = Fs cos theta`
`= Td cos180^(@) = (-3/4Mg) xx d = -3Mg(d)/4`
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