A load o f 1 kg weight is a attached to one end of a steel wire o f area of cross-section `3mm^(2)` and Young's modulus `10^(11) N//m^(2)` . The other end is suspended vertically from a hook on a wall , then the load is pulled horizontally and released .When the load passes through its lowest position the fraction al change in lenght is `(Take g = 10m//s^(2))`

Options

A. ` 0.3 xx 10 ^(-4)`
B. `0.3 xx 10^(-3)`
C. `0.3 xx 10 ^(3)`
D. `0.3 xx 10 ^(4)`

Answer

A

Explanation

(a) `Y=(mgl)/(ADeltal)`
`implies (Deltal)/(l)=(mg)/(AY)`
`therefore (Deltal)/(l)=(1xx10)/(3xx10^(-6)xx10^(11))`
`=0.3xx10^(-4)`