Physics Elasticity Question 157
Question: Two wires A and B are of same materials. Their lengths are in the ratio 1 : 2 and diameters are in the ratio 2 : 1 when stretched by force $ F _{A} $ and $ F _{B} $ respectively they get equal increase in their lengths. Then the ratio $ F _{A}/F _{B} $ should be
[Orissa JEE 2002]
Options:
A) 1 : 2
B) 1 : 1
C) 2 : 1
D) 8 : 1
Show Answer
Answer:
Correct Answer: D
Solution:
$ F=Y\times A\times \frac{l}{L} $
Therefore $ F\propto \frac{r^{2}}{L} $ (Y and l are constant) $ \frac{F _{A}}{F _{B}}={{\left( \frac{r _{A}}{r _{B}} \right)}^{2}}\times \left( \frac{L _{B}}{L _{A}} \right)={{\left( \frac{2}{1} \right)}^{2}}\times \left( \frac{2}{1} \right)=\frac{8}{1} $
BETA
