A projectile is thrown with some initial velocity at an angle $\alpha$ to the horizontal. Its velocity when it is at the highest point is $(2 / 5)^{1 / 2}$ times the velocity when it is at height half of the maximum height. Find the angle of projection $\alpha$ with the horizontal.
$30$
$45$
$60$
$37$
The horizontal range is four times the maximum height attained by a projectile. The angle of projection is .......... $^o$
A ball is projected from ground with a velocity $V$ at an angle $\theta$ to the vertical. On its path it makes an elastic collison with a vertical wall and returns to ground. The total time of flight of the ball is
The $x-t$ graph of a particle moving along a straight line is shown in figure The $v-t$ graph of the particle is correctly shown by
In projectile motion, the modulus of rate of change of velocity
At the top of the trajectory of a projectile, the directions of its velocity and acceleration are