A and B are two wires. The radius of A is twice that of B. They are stretched by the some load. The the stress on B is

Options

A. Remains same
B. 2 times of A
C. 3 times of A
D. 9 times of A

Answer

D

Explanation

Stress `= ("force")/("Area")` Stress `prop (1)/(delta r^(2))`
`(S_(Y))/(S_(A))= (r_(A)^(2))/(r_(B)^(2))= (3)^(2) = 9S_(A)`