$A$ particle is projected from the ground at an angle of $\theta$ with the horizontal with an initial speed of $u$. The time after which the velocity vector of the projectile is perpendicular to the initial velocity is:

$A$ body is projected horizontally from the top of a tall tower with a velocity of $30 \,ms^{-1}$. At time $t_1$, its horizontal and vertical components of the velocity are equal and at time $t_2$, its horizontal and vertical displacements are equal. Then $t_2-t_1$ is (take, $g=10 \,ms^{-2}$ ) (in $\,s$)

Simultaneously,from the top of a tower,when ball-$1$ is thrown horizontally and ball-$2$ is just dropped,in the absence of air resistance,which among the following options is correct?

$A$ ball rolls from the top of a stairway with a horizontal velocity $u \; m/s$. If the steps are $h \; m$ high and $b \; m$ wide,the ball will hit the edge of the $n^{th}$ step,if $n=$

$A$ player kicks a football with an initial speed of $25\, ms^{-1}$ at an angle of $45^{\circ}$ from the ground. What are the maximum height and the time taken by the football to reach the highest point during motion? (Take $g = 10\, ms^{-2}$)

$A$ fighter plane, flying horizontally with a speed of $360 \text{ km/h}$ at an altitude of $500 \text{ m}$, drops a bomb for a target straight ahead of it on the ground. At what approximate distance ahead of the target should the bomb be dropped? Assume that acceleration due to gravity $g = 10 \text{ m/s}^2$. Neglect air drag.