Physics Elasticity Question 161
Question: A wire of length 2 m is made from $ 10\ cm^{3} $ of copper. A force F is applied so that its length increases by 2 mm. Another wire of length 8 m is made from the same volume of copper. If the force F is applied to it, its length will increase by
[MP PET 2003]
Options:
A) 0.8 cm
B) 1.6 cm
C) 2.4 cm
D)3.2 cm
Show Answer
Answer:
Correct Answer: D
Solution:
$ l=\frac{FL}{AY}=\frac{FL^{2}}{(AL)Y}=\frac{FL^{2}}{VY} $ \ $ l\propto L^{2} $ If volume of the wire remains constant $ \frac{l _{2}}{l _{1}}={{\left( \frac{L _{2}}{L _{1}} \right)}^{2}}={{\left( \frac{8}{2} \right)}^{2}}=16 $ $ l _{2}=16\times l _{1}=16\times 2=32mm=3.2cm $
BETA
