Physics Elasticity Question 61
Question: The length of a rod is 20 cm and area of cross-section $ 2,cm^{2} $ . The Young’s modulus of the material of wire is $ 1.4\times 10^{11},N/m^{2} $ . If the rod is compressed by 5 kg-wt along its length, then increase in the energy of the rod in joules will be
Options:
A) $ 8.57\times {{10}^{-6}} $
B) $ 22.5\times {{10}^{-4}} $
C) $ 9.8\times {{10}^{-5}} $
D) $ 45.0\times {{10}^{-5}} $
Show Answer
Answer:
Correct Answer: A
Solution:
Energy = $ \frac{1}{2}Fl=\frac{1}{2}\times F\times \left( \frac{FL}{AY} \right)=\frac{1}{2}\times \frac{F^{2}L}{AY} $
$ =\frac{1}{2}\times \frac{{{(50)}^{2}}\times 20\times {{10}^{-2}}}{2\times {{10}^{-4}}\times 1.4\times 10^{11}} $
$ =8.57\times {{10}^{-6}}J $
BETA
