A sphere of radius 0.1 mand mass `8 pi `kg is attached to the lower end of a steel wire of length 5 mand diamet `10^(@)`m. The wire is suspended from 5.22 m high ceiling of a room. When sphere is made to swing, it just graz the floor at its lowest point, due to the clongation Y for stoel is `2 xx 10^(11)' N//m^(2)',g=10 m//s^(2)`

The extension of wire wher, the sphere is at lowest point. (Approximately)

Options

A. `0.2 ` m
B. `0.02` m
C. 2 m
D. `0.002 ` m

Answer

B

Explanation

Original length =5 m when it touches the ground the length = 5.22 -0.2 = 5.02
Extension = 5.02 -5.00 = 0.02 m
Tension `F = (W Al)/(L) = (2xx 10^(11) xx pi(0.0005)^(2)xx0.02)/(5) = 200 pi N`