Question 11: Let a wire be suspended from the ceiling (rigid support) and stretched by a weight W attached at its free end. The longitudinal stress at any point of cross-sectional area A of the wire is :
(1) \frac{W}{2A}
(2) Zero
(3) \frac{2W}{A}
(4) \frac{W}{A}
Answer: Option (4)
Explanation:
When a wire is suspended from a rigid support and a weight W is attached at its free end,
the wire experiences a tensile force equal to the applied weight.
The same force W acts throughout the length of the wire
because the system is in equilibrium.
Longitudinal stress is defined as the ratio of the applied force to the cross-sectional area of the wire.
\text{Longitudinal stress}=\frac{\text{Force}}{\text{Area}}Substituting the given values,
\text{Stress}=\frac{W}{A}Thus, the longitudinal stress at any point of the wire is \frac{W}{A}.