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...........$s$ $(g = 10\,ms^{-2})$.

$A$ window is $50\,cm$ long. $A$ stone is falling from a height of $40\,cm$ above the window. It crosses the window in

$A$ boy throws balls into the air at a regular interval of $2 \, s$. The next ball is thrown when the velocity of the first ball is zero. How high does the ball rise above his hand (in $, m$)? [Take $g = 9.8 \, m/s^2$]

$A$ body is projected vertically upwards. The times corresponding to a specific height while ascending and while descending are $t_{1}$ and $t_{2}$ respectively. Then the velocity of projection is (where $g$ is acceleration due to gravity).

$A$ stone is dropped from a height of $100 \ m$,while another one is projected vertically upwards from the ground with a velocity of $25 \ m/s$ at the same time. The time in seconds after which they will have the same height is (acceleration due to gravity,$g = 10 \ m/s^2$):

$A$ ball of mass $0.2 \, kg$ is thrown vertically upwards with a velocity of $2 \, m/s$. At the highest point of its trajectory:
$(i)$ What will be the magnitude of its velocity?
$(ii)$ What will be the magnitude of its acceleration?
$(iii)$ What will be the magnitude of the force acting on it? (Take $g = 10 \, m/s^2$.)