Mechanical Properties Of Solids Question 10
Question 10 - 01 February - Shift 2
The Young’s modulus of a steel wire of length $6 m$ and cross-sectional area $3 mm^{2}$, is $2 \times 11^{11} N / m^{2}$. The wire is suspended from its support on a given planet. A block of mass $4 kg$ is attached to the free end of the wire. The acceleration due to gravity on the planet is $\frac{1}{4}$ of its value on the earth. The elongation of wire is (Take $g$ on the earth $=10$ $.m / s^{2})$ :
(1) $1 cm$
(2) $1 mm$
(3) $0.1 mm$
(4) $0.1 cm$
Show Answer
Answer: (3)
Solution:
Formula: Young’s modulus
Tension $(F)=m g$
$ =4 \times \frac{10}{4}=10 N $
$\Delta L=\frac{FL}{AY}$
$=\frac{10 \times 6}{3 \times 10^{-6} \times 2 \times 10^{11}}$
$=10^{-4} m=0.1 mm$
