$A$ boy throws a cricket ball from the boundary to the wicket keeper. If the frictional force due to air $f_a$ cannot be ignored,the forces acting on the ball at the position $X$ are represented by

Derive the expressions for the time taken to reach maximum height,the total time of flight,and the maximum height attained by a projectile.

$A$ particle of mass $m$ moves along a circular path of radius $r$ with a time-dependent centripetal acceleration $a_c = k^2rt^2$,where $k$ is a constant. What is the power delivered to the particle by the force acting on it?

Balls $A$ and $B$ are thrown from two points lying on the same horizontal plane separated by a distance of $120\,m$. Which of the following statement$(s)$ is/are correct?

$A$ person sitting in an open car moving at a constant velocity throws a ball vertically up into the air. The ball falls:

$A$ particle at a distance of $1 \ m$ from the origin starts moving,such that $dr/d\theta = r$,where $r$ and $\theta$ are polar coordinates. Then,the angle between the resultant velocity and the tangential velocity is