$A$ stone is projected at an angle of $60^o$ from the ground level and strikes at an angle of $30^o$ on the roof of a building of height $h = 30 \, m$. Find the speed of projection (in $m/s$) of the stone.

$A$ cannon placed on a cliff at a height of $375 \ m$ fires a cannonball with a velocity of $100 \ ms^{-1}$ at an angle of $30^{\circ}$ above the horizontal. The horizontal distance between the cannon and the target is (Acceleration due to gravity $= 10 \ ms^{-2}$)

$A$ 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 $2h$ 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

An aeroplane flying $490 \, m$ above ground level at $100 \, m/s$ releases a block. How far on the ground will it strike (in $km$)?

There are three steps,each with a height of $10 \, cm$ and a width of $20 \, cm$. What minimum horizontal velocity (in $m/s$) must be given to a ball from the top step so that it clears all three steps?

$A$ ball is thrown upward from the top of a building at an angle of $30^{\circ}$ to the horizontal and with an initial speed of $20 \,m/s$. If the ball strikes the ground after $3 \,s$, then the height of the building is (acceleration due to gravity $g = 10 \,m/s^2$) (in $\,m$)