Question

One end of a uniform wire of length L and of weight 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, the stress in the wire at a height $\frac{3L}{4}$ from its lower end is

• A.
  
• B.
  
• C.
• D.

Answer 1

The correct option is C

As the wire is uniform so the weight of wire below point P is $\frac{3W}{4}$
$\therefore$ Total force at point $P=W_1+\frac{3W}{4}$
and area of cross-section = S
$\therefore$ Stress at point $P=\frac{Force}{Area}=\frac{W_1+\frac{3W}{4}}{S}$