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A wire elongates by l units, when a load...

A wire elongates by `l` units, when a load `w` is suspended from it . If the wirew gets over a pulley ( equally on both the sides ) and two weights `w` each are hung at the two ends, the elongation of wire (in units ) will be

A

`Zero `

B

`1/2`

C

`l`

D

`2l`

Text Solution

Verified by Experts

The correct Answer is:
C

Extension in the first case is
`l = (FL)/(AY) = (wL)/(AY)`
Extension in the second case is
`l' =(w(L//2))/(AY)+(w(L//2))/(AY) =(wL)/(AY) ` It is clear that `l' = l`
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Knowledge Check

  • A wire elongates by l mm when a load W is hanged from it. It the wire goes over a pulley and two weights W each are hung at the two ends, the elongation of the wire (in mm) will be

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    `(l)/(2)`
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