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One end of a steel wire is fixed to c...

One end of a steel wire is fixed to celling of an elevator moving up load of 10 g hange from other end. Area of cross-section of the wire Is `2 cm^(2)`.Find the longitudinal strain in the wire `(Take g = 10m//s^(2) and Y= 2 xx 10^(11) N//m^(2))`

A

` 4 xx 10^(11)`

B

` 3 xx 10^(-6)`

C

`8 xx10^(-6)`

D

`2 xx 10 ^(-6)`

Text Solution

Verified by Experts

The correct Answer is:
B
Here , T = `m(g + a_(0)) = 10 (10 +2)= 120 N`
`therefore" "Stress=(T)/(A)=(120)/(2 xx 10 ^(-4))`

`=60 xx 10^(4)n//m^(2)` `therefore " " Y = ("stress")/("strain")`
`therefore"Strain"= ("stress")/(Y) = (60xx 10^(4))/( 2 xx 10^(11))= 30 xx 10 ^(-7)= 3 xx 10 ^(-6)`
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