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

Young's modulus , `Y = (mgL)/(AI) implies (I)/(L) = (mg)/(AY)`
`:. (I)/(L) = (1 xx 10)/(3 xx 10^(-6) xx 10^(11)) = 0.3 xx 10^(-4)`