CMC Medical
CMC-Medical Ludhiana Solved Paper-2014
question_answer
A ball is falling freely from a height. When, it reaches 10 m height from the ground its velocity is \[{{v}_{0}}\]. It collides with the ground and loses 50% of its energy and rises back to height of 10 m. Then, the velocity\[{{v}_{0}}\]is
A) 7 m/s
B) 10 m/s
C) 14 m/s
D) 16 m/s
Correct Answer:
C
Solution :
At height 10 m, the kinetic energy is equal to potential energy, then \[\frac{1}{2}mv_{0}^{2}=mgh\] \[\frac{1}{2}v_{0}^{2}=9.8\times 10\] \[v_{0}^{2}=2\times 9.8\times 10\] \[{{v}_{0}}=\sqrt{196}\] \[{{v}_{0}}=14\,m\text{/}s\]