Q. One end of 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 (3L/4) from its lower end is
A) $\frac{w_{1}}{s}$
B) $\left\lbrack w_{1} + \frac{w}{4} \right\rbrack s$
C) $\left\lbrack w_{1} + \frac{3w}{4} \right\rbrack$ / $s$
D) $\frac{w_{1} + w}{s}$
Explanation
(c) Force = weight suspended + weight of $\frac{3L}{4}\ $of wire
$w_{1} + \frac{3w}{4}$
Stress = $\frac{force}{area} = \ \frac{W_{1} + \frac{3}{4}w}{5}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.