Q.
A steel wire of cross-sectional area $3\ \times 10^{- 6}m^{2}$ can withstand a maximum strain of $10^{- 3}$ . Young’s modulus of steel is $2 \times 10^{11}{Nm}^{- 2}$. The maximum mass the wire can hold is$\ \ (take\ g = 10\ {ms}^{- 2\ })$
A) 40 kg
B) 60 kg
C) 80 kg
D) 100 kg
Explanation
(b) Young’s modulus $Y = \frac{Stress}{Strain} = \frac{\frac{F}{A}}{Strain}$
or $Y\frac{mg}{A \times strain}$
or $\ m = \frac{Y \times A \times strain}{g}$
$= \frac{2 \times 10^{11} \times 10^{- 3} \times 10^{- 6}}{10} = 60kg$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.