Balls are thrown vertically upward in such a way that the next ball is thrown when the previous one is at the maximum height. If the maximum height is $5 \ m$,the number of balls thrown per minute will be

$A$ player throws a ball upwards with an initial speed of $29.4 \; m s^{-1}$. What is the direction of acceleration during the upward motion of the ball?

$A$ body freely falling from rest has a velocity $v$ after it falls through a height $h$. The total distance it has to fall down from the starting point for its velocity to become double is: (in $h$)

$A$ body is projected vertically upwards at time $t=0$ and it is seen at a height $H$ at times $t_1$ and $t_2$ seconds during its flight. The maximum height attained is ($g$ is acceleration due to gravity).

$A$ boy throws a ball vertically upwards from a bridge with velocity $5 \ m/s$. It strikes the water surface after $2 \ s$. The height of the bridge is (Take $g = 10 \ m/s^2$) (in $m$)

$A$ ball is dropped from a high-rise platform at $t=0$ starting from rest. After $6$ seconds,another ball is thrown downwards from the same platform with a speed $v$. The two balls meet at $t=18\,s$. What is the value of $v$ in $m/s$? (Take $g= 10\,m/s^2$)