A boy throws balls into air at regular interval of 2 second. The next ball is thrown when the velocity of first ball is zero. How high do the ball rise above his hand? [Take g=9.8 m/s2].
Velocity of a ball becomes zero when the ball is at maximum height.
The interval is 2 s, which means that after the 1 st ball reaches max height at that time 2nd ball is thrown
It means time of ascent of ball is 2 s
So, time of ascent= u/g = 2
So u= 19.6 m/s
Then ,the max height= u^2/2g =19.6*19.6/2*9.8
Max height = 19.6 m