Physics Elasticity Question 128
Question: Two wires ?A? and ?B? of the same material have radii in the ratio 2 : 1 and lengths in the ratio 4 : 1. The ratio of the normal forces required to produce the same change in the lengths of these two wires is
[Haryana CEE 1996]
Options:
A) 1 : 1
B) 2 : 1
C) 1 : 4
D) 1 : 2
Show Answer
Answer:
Correct Answer: A
Solution:
$ F=Y\times A\times \frac{l}{L} $
Therefore $ F\propto \frac{r^{2}}{L} $ (Y and l are constant) $ \frac{F _{1}}{F _{2}}={{\left( \frac{r _{1}}{r _{2}} \right)}^{2}}\left( \frac{L _{2}}{L _{1}} \right)={{\left( \frac{2}{1} \right)}^{2}}\left( \frac{1}{4} \right)=1 $
Therefore $ \frac{F _{1}}{F _{2}}=1:1 $
BETA
