A man is travelling on a flat car which is moving up a plane inclined at $\cos \theta =\frac{4}{5}$ to the horizontal with a speed $5 \mathrm{m} {\mathrm{s}}^{-1}$. He throws a ball towards a stationary hoop located perpendicular to the incline in such a way that the ball moves parallel to the slope of the incline while going through the centre of the hoop. The centre of the hoop is $4 \mathrm{m}$ high from the man's hand calculate the time taken (in $\mathrm{s}$) by the ball to reach the hoop in second. 

A stone is projected horizontally with speed $V$ from a height $h$ above ground. A horizontal wind is blowing in a direction opposite to the velocity of projection and gives the stone a constant horizontal acceleration $f$ (in a direction opposite to the initial velocity). As a result, the stone falls on the ground at a point vertically below the point of projection. Then find the value of $\frac{f^{2}h}{g{V}^2}$.

($g$ is acceleration due to gravity)

Two stones are projected from the level ground. Trajectories of two stones are shown in the figure. Both stones have same maximum heights above level ground as shown. Let $T_1$ and $T_2$ be their time of flights and $u_1$ and $u_2$ be their speeds of projection respectively (neglect air resistance). Then