$A$ cannon ball is fired from the top of a $55 \ m$ high cliff with an initial speed of $50 \ m \ s^{-1}$. The speed of the cannon ball while hitting the ground in $m \ s^{-1}$ is (acceleration due to gravity $= 10 \ m \ s^{-2}$):

An aeroplane moving horizontally with a speed of $180\, km/hr$ drops a food packet while flying at a height of $490\, m$. The horizontal range is........$m$.

The figure shows a projectile thrown with a speed $u = 20 \, m/s$ at an angle of $30^{\circ}$ with the horizontal from the top of a building $40 \, m$ high. The horizontal range of the projectile is ........... $m$.

There are three steps,each with a height of $10 \, cm$ and a width of $20 \, cm$. What minimum horizontal velocity (in $m/s$) must be given to a ball from the top step so that it clears all three steps?

$A$ hiker stands on the edge of a cliff $490 \; m$ above the ground and throws a stone horizontally with an initial speed of $15 \; m/s$. Neglecting air resistance,find the time taken by the stone to reach the ground,and the speed with which it hits the ground. (Take $g = 9.8 \; m/s^2$).

$A$ ball is thrown from a rooftop at an angle of $45^\circ$ above the horizontal. It hits the ground a few seconds later. At what point during its motion does the ball have $(a)$ greatest speed, $(b)$ smallest speed, and $(c)$ greatest acceleration? Explain.