$A$ boy is standing on top of a tower of height $85 \, m$ and throws a ball in the vertically upward direction with a certain speed. If $5.25 \, s$ later he hears the ball hitting the ground,then the speed with which the boy threw the ball is .......... $m/s$ (take $g = 10 \, m/s^2$ and speed of sound in air $= 340 \, m/s$).

$A$ boy standing on a stationary lift (open from above) throws a ball upwards with the maximum initial speed he can,equal to $49\; m s^{-1}$. How much time does the ball take to return to his hands? If the lift starts moving up with a uniform speed of $5\; m s^{-1}$ and the boy again throws the ball up with the maximum speed he can,how long does the ball take to return to his hands?

$A$ player throws a ball upwards with an initial speed of $29.4 \; m s^{-1}$. To what height does the ball rise and after how long (in seconds) does the ball return to the player's hands? (Take $g = 9.8 \; m s^{-2}$ and neglect air resistance).

Which of the following statements is correct?

Consider the acceleration,velocity,and displacement of a tennis ball as it falls to the ground and bounces back. The directions of which of these change during the process?

$A$ ball dropped from the top of a tower falls the first half of the height of the tower in $10 \, s$. The total time spent by the ball in the air is ......... $s$. [Take $g = 10 \, m/s^2$]