A steel rod has radius 50 mm and length 2 m. It is stretched along its length with a force of 400 KN. This causes an elongation of 0.5 mm. Find the (approximate) Young's modulus of steel from this information. 

Options

A. `2xx10^(10)Nm^(2)`
B. `10^(11)Nm^(2)`
C. `2xx10^(11)Nm^(2)`
D. `10^(12)Nm^(2)`

Answer

C

Explanation

Given, `F=400" kN"=400xx10^(3)N`
L = 2m
`r=50" mm"=5xx10^(2)m`
`Deltal=0.5" mm"=5xx10^(-4)m`
Young's modulus, `Y=(F.L)/(A.Deltal)`
`=(4xx10^(5)xx2xx10^(4)xx10^(4))/((22)/(7)xx25xx5)=(8xx7)/(22xx5xx25)xx10^(13)`
`~~2xx10^(11)Nm^(2)`