An aeroplane is moving horizontally with a velocity of $u.$ It drops a packet from a height $h.$ The time taken by the packet in reaching the ground will be

If time taken by the projectile to reach $B$ is $T,$ then $AB$ is equal to

The small marble is projected with a velocity of $10 \mathrm{m} {\mathrm{s}}^{-1}$ in a direction $45°$ from the horizontal $y$-direction on the smooth inclined plane. Calculate the magnitude $v$ of its velocity after $2 \mathrm{s}$.