Due to the presence of air resistance,if a body dropped from a height of $20 \ m$ reaches the ground with a speed of $18 \ m/s$,then the time taken by the body to reach the ground is nearly (in $s$)

$A$ particle is dropped under gravity from rest from a height $h$ $(g = 9.8 \ m/s^2)$. If it travels a distance of $9h/25$ in the last second of its motion,the height $h$ is ......... $m$.

$A$ body is dropped from a height $h$. It covers a distance of $9h/25$ in the last second of its motion. What is the height $h$ in $m$?

$A$ ball is thrown vertically upward with an initial velocity of $150\,m/s$. The ratio of velocity after $3\,s$ and $5\,s$ is $\frac{x+1}{x}$. The value of $x$ is $...........$ Take $g=10\,m/s^2$.

$A$ body falls freely from rest. It covers as much distance in the last second of its motion as it covers in the first three seconds. The body has fallen for a total time of ........ $s$.

$A$ man in a balloon rising vertically with an acceleration of $4.9 \, m/s^2$ releases a ball $2 \, s$ after the balloon is let go from the ground. The greatest height above the ground reached by the ball is .......... $m$ :-