Physics Elasticity Question 93

Question: To double the length of a iron wire having $ 0.5,cm^{2} $ area of cross-section, the required force will be $ (Y=10^{12},dyne/cm^{2}) $

[MP PMT 1987]

Options:

A) $ 1.0\times {{10}^{-7}}N $

B) $ 1.0\times 10^{7}N $

C) $ 0.5\times {{10}^{-7}}N $

D) $ 0.5\times 10^{12} $ dyne

Show Answer

Answer:

Correct Answer: D

Solution:

If length of wire doubled then strain = 1 $ Y=r $

Therefore $ F=Y\times A $

$ =10^{12}\times 0.5 $

$ =0.5\times 10^{12}dyne $