Question 159: Motion in 1D

Question

A man throws balls 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/s2)

Accepted Answer

When more than two balls means minimum three balls are in the sky then time of flight for the first ball should be more than 4 s.
T > 4 s
$${{2u} \over g}$$ > 4
$$ \Rightarrow $$ u > 19.6 m/s

Answer

more than 19.6 m/s

Answer

at least 9.8 m/s

Answer

any speed less than 19.6 m/s

Answer

only with speed  19.6 m/s.

Motion in 1D

A man throws balls 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/s2)

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