From the top of a tower of height $40\, m$, a ball is projected upwards with a speed of $20\, m/s$ at an angle $30^o$ to the horizontal. The ball will hit the ground in time ......... $\sec$ (Take $g = 10\, m/s^2$)

At what angle of elevation, should a projectile be projected with velocity $20 \,ms ^{-1}$, so as to reach a maximum height of $10 \,m$ ?

A missile is fired for maximum range with an initial velocity of $20\; m/s$. If $g = 10 \;m/s^2$ , the range of the missile is ...... $m$

A ball is projected from ground at an angle $45^{\circ}$ with horizontal from distance $d_1$ from the foot of a pole and just after touching the top of pole it the falls on ground at distance $d_2$ from pole on other side, the height of pole is ...........

The position coordinates of a projectile projected from ground on a certain planet (with no atmosphere) are given by $y=\left(4 t-2 t^2\right) m$ and $x =(3 t)$ metre, where $t$ is in second and point of projection is taken as origin. The angle of projection of projectile with vertical is .........

The maximum horizontal range of a projectile is $16\,km$ when the projectile is thrown at an elevation of $30^o$ from the horizontal, it will reach to the maximum height of ....... $km$