Question

A and B are two steel wires and the radius of A is twice that of B. If they are stretched by the same load, then the stress on B is .....

Options

• four times that of A.

• two times that of A.

• three times that of A.

• same as that of A.

Answer 1

four times that of A.

(r_A=2r_B) ............(1)

`therefore stress=F/A`

`stress prop1/r^2`

`therefore (stress_A)/(stress_b)=r_B^2/r_A^2`

`"Stress of B"=r_A^2/r_B^2 xx " stress of "A`

`"Stress of B"=(2r_B)^2/r_B^2 xx " stress of "A`  .............. from equation 1

`"Stress of B"=(4r_B^2)/r_B^2 xx " stress of "A`

`"Stress on B"=4* "Stress on A"`