Question

One end of a unifrom wire of length L and weigth W is attached rigidly to a point in the roof and a weight `W_(1)` is suspended from its lower end. If S is the area of cross-section of the wire then the stress in the wire at a height `(3L)/(4)` from its lower end is
A. `((W_(1) + W))/(S)`
B. `(W_(1))/(S)`
C. `((W_(1) + (3W)/(4)))/(S)`
D. `((W_(1) + (W)/(4)))/(S)`

Answer 1

Correct Answer - c
Downward force acting at A
= weight of `(3)/(4)` length of the wire + weight attached `W_(1)`
`= (3)/(4) W + W_(1)`
`:.` Stress `= (F)/(A) = (W_(1) + (3)/(4) W)/(S)`