Physics Elasticity Question 98
Question: Increase in length of a wire is 1 mm when suspended by a weight. If the same weight is suspended on a wire of double its length and double its radius, the increase in length will be
[CPMT 1976]
Options:
A) 2 mm
B) 0.5 mm
C) 4 mm
D) 0.25 mm
Show Answer
Answer:
Correct Answer: B
Solution:
$ l=\frac{FL}{AY}\Rightarrow l\propto \frac{L}{r^{2}} $ (F and Y are same) $ \frac{l _{2}}{l _{1}}=\frac{L _{2}}{L _{1}}{{\left( \frac{r _{1}}{r _{2}} \right)}^{2}}=2\times {{\left( \frac{1}{2} \right)}^{2}}=\frac{1}{2} $
Therefore $ l _{2}=\frac{l _{1}}{2}=\frac{l}{2}=0.5mm. $
BETA
