Kinematics Question 176

Question: A ball is dropped on the floor from a height of 10 m. It rebounds to a height of 2.5 m. If the ball is in contact with the floor for 0.01 sec, the average acceleration during contact it’s [BHU 1997; CPMT 1997]

Options:

A) 2100 m/sec2 downwards

B) 2100 m/sec2 upwards

C) 1400 m/sec2

D) 700 m/sec2

Show Answer

Answer:

Correct Answer: B

Solution:

Velocity at the time of striking the floor,

u=2gh1=2×9.8×10=14m/s Velocity with which it rebounds.

v=2gh2=2×9.8×2.5=7 m/s

Change in velocity Δv=7(14)=21m/s

Acceleration =ΔvΔt=210.01=2100 m/s2 (upwards)



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