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In the fig., the ends P and Q of an unst...

In the fig., the ends P and Q of an unstrechable string move downwards with uniform speed V. Mass M moves upwards with speed.

A

`v cos theta`

B

`v/(cos theta)`

C

`2v cos theta`

D

`2/(v cos theta)`

Text Solution

Verified by Experts

The correct Answer is:
B

Here `x^(2)=y^(2)+d^(2)`
So `2x(dx)/(dt)=2y(dy)/(dt)rArr (dy)/(dt)=(x/y)((dx)/(dt))=(x/y)(v)=v/(cos theta)`
OR
Component of velocity along string must be same
so `v_(M) cos theta=vrArr v_(M)=v/(cos theta)`
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