$A$ player throws a ball that reaches another player in $4\,s$. If the height of each player is $1.5\,m$,the maximum height attained by the ball from the ground level is .......... $m$.

At a height $0.4\, m$ from the ground,the velocity of a projectile in vector form is $\vec v = (6\hat i + 2\hat j)\,m/s$. The angle of projection is ...... $^o$ $(g = 10\, m/s^2)$.

$A$ bomber plane moves horizontally with a speed of $500\,m/s$ and a bomb released from it,strikes the ground in $10\,s$. The angle with the horizontal at which it strikes the ground will be $(g = 10\,m/s^2)$.

$A$ 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.

$A$ bowling machine placed at a height $h$ above the earth's surface releases different balls with different angles but with the same velocity $10 \sqrt{3} \text{ m s}^{-1}$. All these balls' landing velocities make angles of $30^{\circ}$ or more with the horizontal. Find the height $h$ (in meters) (acceleration due to gravity $g = 10 \text{ m s}^{-2}$).

$A$ ball of mass $m=1 \, kg$ is thrown from the top of a building with initial velocity $v=(20 \, m/s) \hat{i} + (24 \, m/s) \hat{j}$ at time $t=0$. The change in the potential energy of the ball between $t=0$ and $t=6 \, s$, if the ball does not hit the ground, is (assume $g=10 \, m/s^2$): (in $ \, J$)