A particle projected from ground moves at angle $45^{\circ}$ with horizontal one second after projection and speed is minimum two seconds after the projection. The angle of projection of particle is [Neglect the effect of air resistance]
$\tan ^{-1}(3)$
$\tan ^{-1}(2)$
$\tan ^{-1}(\sqrt{2})$
$\tan ^{-1}(4)$
A projectile crosses two walls of equal height $H$ symmetrically as shown The height of each wall is ........ $m$
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
A body is projected with velocity $u$ making an angle $\alpha$ with the horizontal. Its velocity when it is perpendicular to the initial velocity vector $u$ is
A ball is projected vertically upwards with a certain initial speed. Another ball of the same mass is projected with the same speed at an angle of $30^o$ with the horizontal. At the highest point, the ratio of their potential energies is
A ball thrown by one player reaches the other in $2$ sec. the maximum height attained by the ball above the point of projection will be about ....... $m$