Physics Elasticity Question 149
Question: When a uniform wire of radius r is stretched by a 2kg weight, the increase in its length is 2.00 mm. If the radius of the wire is r/2 and other conditions remain the same, the increase in its length is
[EAMCET (Engg.) 2000]
Options:
A) 2.00 mm
B)4.00 mm
C) 6.00mm
D)8.00 mm
Show Answer
Answer:
Correct Answer: D
Solution:
$ l=\frac{FL}{\pi r^{2}Y}\
Therefore l\propto \frac{1}{r^{2}} $ (F,L and Y are constant) $ \frac{l _{2}}{l _{1}}={{\left( \frac{r _{1}}{r _{2}} \right)}^{2}}={{(2)}^{2}}\Rightarrow l _{2}=4l _{1}=4\times 2=8\ mm. $
BETA
