question_answer

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 \[\text{g}=\text{9}.\text{8m}/{{\text{s}}^{\text{2}}}\])

Answer:

Interval of ball thrown = 2 sec. If we want that more than two balls remain in air, then time of flight of first ball must be greater than 4seconds i.e.,\[T>4s.\] \[or\,\,\frac{2u}{g}>4\,\,or\,\,u>\frac{4g}{2}\] \[or\,\,u>\frac{4\times 9.8}{2}\,\,or\,\,u>19.6\,m/s\]