From a balloon moving upwards with a velocity of $12\,ms^{-1}$,a packet is released when it is at a height of $65\,m$ from the ground. The time taken by it to reach the ground is...........$s$ $(g = 10\,ms^{-2})$.

$A$ stone dropped from the top of a tower is found to travel $\left(\frac{5}{9}\right)$ of the height of the tower during the last second of its fall. The time of fall is ....... $s$.

$A$ ball is thrown upwards. It takes $4 \, s$ to reach back to the ground. Its initial velocity is........$m/s$.

$A$ stone is thrown with an initial speed of $4.9 \, m/s$ from a bridge in a vertically upward direction. It falls down into the water after $2 \, s$. The height of the bridge is .......... $m$.

If a body is thrown up with the velocity of $15 \, m/s$,then the maximum height attained by the body is .......... $m$ $(g = 10 \, m/s^2)$.

$A$ ball is projected vertically upwards from the ground. It reaches a height $h$ in time $t_1$,continues its motion,and then takes a time $t_2$ to reach the ground. The height $h$ in terms of $g, t_1$,and $t_2$ is ($g =$ acceleration due to gravity).