A) 5 m/s
B) 10 m/s
C) 15 m/s
D) 20 m/s
Correct Answer: A
Solution :
| Key Idea: Maximum kinetic energy of swing should be equal to difference in potential energies to conserve energy. From energy conservation |
| \[\frac{1}{2}mv_{\max }^{2}=mg({{H}_{2}}-{{H}_{1}})\] |
| Here, \[{{H}_{1}}=\] minimum height of swing from earth's surface = 0.75 m |
| \[{{H}_{2}}=\] maximum height of swing from earth's surface = 2 m |
| \[\therefore \] \[\frac{1}{2}mv_{\max }^{2}=mg\,(2-0.75)\] |
| or \[{{v}_{\max }}=\sqrt{2\times 10\times 1.25}\] |
| \[=\sqrt{25}=5\,m/s\] |
You need to login to perform this action.
You will be redirected in
3 sec
