A) 5: 2
B) 2:5
C) 1 :3
D) 3:1
Correct Answer: B
Solution :
Stretching force \[F=\frac{YA}{L}.\Delta l\] Here, both are of same material (i.e., same Y), same diameter (i.e., same A) and are stretched by same force So, \[\frac{\Delta {{l}_{1}}}{{{L}_{1}}}=\frac{\Delta {{l}_{2}}}{{{L}_{2}}}\] \[\therefore \] \[\frac{\Delta {{l}_{1}}}{\Delta {{l}_{2}}}=\frac{{{L}_{1}}}{{{L}_{2}}}=\frac{2}{5}\] Work done \[W=\frac{1}{2}YA\frac{\Delta {{l}^{2}}}{L}\] Ratio of work done \[\frac{{{W}_{1}}}{{{W}_{2}}}={{\left( \frac{\Delta {{l}_{1}}}{\Delta {{l}_{2}}} \right)}^{2}}.\frac{{{L}_{2}}}{{{L}_{1}}}\] \[={{\left( \frac{2}{5} \right)}^{2}}.\left( \frac{5}{2} \right)\] \[=\frac{2}{5}=2:5\]
You need to login to perform this action.
You will be redirected in
3 sec
