A ball is projected from ground with a velocity $V$ at an angle $\theta$ to the vertical. On its path it makes an elastic collison with a vertical wall and returns to ground. The total time of flight of the ball is
$\frac{{2v\sin \,\theta }}{g}$
$\frac{{2v\cos \,\theta }}{g}$
$\frac{{v\sin \,2\theta }}{g}$
$\frac{{v\cos \,\theta }}{g}$
A particle is projected in air at some angle to the horizontal, moves along parabola as shown in figure where $x$ and $y$ indicate horizontal and vertical directions respectively. Shown in the diagram, direction of velocity and acceleration at points $A, \,B$ and $C$.
If at any point on the path of a projectile its velocity is $u$ at inclination $\alpha$ then it will move at right angles to former direction after time
A stone is projected from the ground with velocity $25\,m/s$. Two seconds later, it just clears a wall $5 \,m$ high. The angle of projection of the stone is ........ $^o$ $(g = 10m/{\sec ^2})$
The equation of motion of a projectile is $y=12 x-\frac{3}{4} x^2$ $..........\,m$ is the range of the projectile.
A cannon on a level plane is aimed at an angle $\theta $ above the horizontal and a shell is fired with a muzzle velocity ${v_0}$ towards a vertical cliff a distance $D$ away. Then the height from the bottom at which the shell strikes the side walls of the cliff is