Question

A steel wire $2\text{m}$ long is suspended from the ceiling. When a mass is hung at its lower end, the increase in length recorded is $1\text{cm}$. Determine the strain in the wire.

• A. $5\times {10}^{-2}$
• B. $5\times {10}^{-3}$
• C. $2.5\times {10}^{-3}$
• D. $2.5\times {10}^{-2}$

Answer 1

The correct option is B $5\times {10}^{-3}$

Given,
Original length $=2\text{m}$
Increase in length $=1\text{cm}=1\times {10}^{-2}\text{m}$
Longitudinal strain $=\frac{\text{Increase in length}}{\text{Original length}}=\frac{\Delta L}{L}$
$=\frac{1\times {10}^{-2}\text{m}}{2\text{m}}=5\times {10}^{-3}$