J & K CET Medical
J & K - CET Medical Solved Paper-2012
question_answer
A rubber ball is bounced on the floor of a room which has its ceiling at a height of 3.2 m from the floor. The ball hits the floor with a speed of 10 m/s and rebounds vertically up. If all collisions simply reverse the velocity of the ball, without changing its speed, then how long does it take the ball for a round trip, from the moment it bounces from the floor to the moment it returns back to it? Acceleration due to gravity is\[10\text{ }m/{{s}^{2}}\].
A) 4s
B) 2s
C) 0.8 s
D) 1.2 s
Correct Answer:
C
Solution :
Time, \[t=\sqrt{\frac{2h}{g}}\] \[=\sqrt{\frac{2\times 3.2}{10}}\] \[=0.8s\]