A load of 4.0 kg is suspended from a celling through a streel wire of length 2.0 m and radius 2.0 mm. It is found that the length of the wire increases by 0.031 mm as equilibrium is achieved. Taking `g = 3.1 pi ms^(-2)` the Young's modulus of steel is

Options

A. `2.0 10^(8) Nm^(-2)`
B. `2.0 xx 10^(9) Nm^(-2)`
C. `2.0 xx 10^(11) Nm^(-2)`
D. `2.0 xx 10^(13) Nm^(-2)`

Answer

c

Explanation

`Y = (MgL)/(pi r^(2) I)`
`= (4 xx (3.1 pi) xx 2.0)/(pi xx (2 xx 10^(-3))^(2) xx 0.031 xx 10^(-3)) = 2 xx 10^(11) Nm^(-2)`