$A$ ball is projected upwards from the top of a tower with a velocity $50 \, m/s$ making an angle $30^\circ$ with the horizontal. The height of the tower is $70 \, m$. After how many seconds from the instant of throwing will the ball reach the ground? ........ $s$

$A$ gun can fire shells with maximum speed $v_0$ and the maximum horizontal range that can be achieved is $R = \frac{v_0^2}{g}$. If a target farther away by distance $\Delta x$ (beyond $R$) has to be hit with the same gun,show that it could be achieved by raising the gun to a height at least $h = \Delta x \left[ 1 + \frac{\Delta x}{R} \right]$.

Projectiles $A$ and $B$ are thrown at angles of $45^{\circ}$ and $60^{\circ}$ with the vertical,respectively,from the top of a $400 \ m$ high tower. If their ranges and times of flight are the same,the ratio of their speeds of projection $v_A : v_B$ is:

$A$ ball is projected from the top of a tower with a velocity of $5 \, m/s$ at an angle of $53^o$ to the horizontal. Its speed when it is at a height of $0.45 \, m$ from the point of projection is ........ $m/s$.

$A$ cricket bowler releases the ball in two different ways:
$(a)$ giving it only horizontal velocity,and
$(b)$ giving it horizontal velocity and a small downward velocity.
The speed $V_s$ at the time of release is the same. Both are released at a height $H$ from the ground. Which one will have greater speed when the ball hits the ground? Neglect air resistance.

$A$ helicopter flying horizontally with a speed of $360 \ km/h$ at an altitude of $2 \ km$,drops an object at an instant. The object hits the ground at a point $O$,$20 \ s$ after it is dropped. The displacement of $O$ from the position of the helicopter where the object was released is: (use acceleration due to gravity $g = 10 \ m/s^2$ and neglect air resistance)