Shots are fired from the top of a tower and from its bottom simultaneously at angles $30^o$ and $60^o$ as shown. If horizontal distance of the point of collision is at a distance $'a'$ from the tower then height of tower $h$ is :

A ball of mass $160\, g$ is thrown up at an angle of $60^{\circ}$ to the horizontal at a speed of $10 \,m / s$. The angular momentum of the ball at the highest point of the trajectory with respect to the point from which the ball is thrown is nearly $\left(g=10\, m / s ^{2}\right)$ (in $kgm ^{2} / s$)

The equation of a projectile is $y =\sqrt{3} x -\frac{ gx ^2}{2}$ the angle of projection is

For angles of projection of a projectile at angle $(45^o  +\theta)$ and $(45^o  -\theta ) $ , the horizontal range described by the projectile are in the ratio of 

Choose the correct alternative $(s)$

A stone is projected from a point on the ground so as to hit a bird on the top of a vertical pole of height $h$ and then attain a maximum height $2 h$ above the ground. If at the instant of projection the bird flies away horizontally with a uniform speed and if the stone hits the bird while descending, then the ratio of the speed of the bird to the horizontal speed of the stone is