. A man throws the ball with the same speed vertically upwards one

after the other at an interval of 2 seconds. What should be the speed of the throw so that more than two balls are in the sky at any time? (Given g = 9.8 m/s^2)

A: More than 19.6 m/s

B: At least 9.8 m/s

C: Any speed less than 19.6 m/s

D: Only with speed 19.6 m/s


Best Answer


Given:t =2s ;g =9.8 m/s2

When the ball is thrown upward the final velocity become zero.i.e v =0

Now, Time taken by ball to reach maximum height

v =u - gt

O =u - gt

u = gt

On substituting the given, we get

u =9.8×2

u = 19.6 m/s

As a result, when he throws a ball at a minimum speed of in19.6 m/s a 2s time period, two balls can be in the air at the same moment.

Final Answer

The correct answer is A i.e More than 19.6 m/s.


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