$A$ projectile is thrown from a point in a horizontal plane such that the horizontal and vertical velocities are $9.8 \; m/s$ and $19.6 \; m/s$ respectively. It will strike the plane after covering a horizontal distance of ........ $m$.

On a planet,a particle is thrown with a velocity $\vec{V} = 6 \hat{i} + (20 - 4t) \hat{j}$. Match the lists. (All quantities are in $SI$ units)

$P$. Time of flight	$1$. $3$
$Q$. Time when particle is moving at an angle of $53^{\circ}$ with horizontal in upwards direction.	$2$. $10$
$R$. Range of the particle	$3$. $50$
$S$. Maximum height reached by the particle	$4$. $60$

For a projectile,the ratio of the maximum height reached to the square of the time of flight is:

$A$ boy throws a ball into the air at $45^{\circ}$ from the horizontal to land it on the roof of a building of height $H$. If the ball attains maximum height in $2 \text{ s}$ and lands on the building in $3 \text{ s}$ after launch,then the value of $H$ is . . . . . . $\text{m}$. $(g = 10 \text{ m/s}^2)$

The time of flight of an object projected with speed $20 \, m/s$ at an angle $30^{\circ}$ with the horizontal is .... $s$.

$A$ projectile is fired from level ground at an angle $\theta$ above the horizontal. The elevation angle $\phi$ of the highest point as seen from the launch point is related to $\theta$ by the relation