With what velocity should a ball be projected vertically so that the distance covered by it in the $5^{th}$ second is twice the distance it covers in its $6^{th}$ second? (Take $g = 10 \, m/s^2$)

$A$ ball is dropped from a bridge of $122.5 \ m$ above a river. After the ball has been falling for $2 \ s$,a second ball is thrown straight down after it. What is the initial velocity of the second ball so that both hit the water at the same time (in $m/s$)?

$A$ body is released from the top of a tower of height $H \, m$. After $2 \, s$ it is stopped and then instantaneously released. What will be its height from the ground after the next $2 \, s$?

$A$ body is projected vertically upward from the surface of the Earth. If the upward direction is taken as positive,then the acceleration of the body during its upward and downward journey are respectively:

Two balls $A$ and $B$ are thrown with the same velocity $u$ from the top of a tower of height $h$. Ball $A$ is thrown vertically upwards and ball $B$ is thrown vertically downwards. If $t_A$ and $t_B$ are the respective times taken by the balls $A$ and $B$ to reach the ground,then identify the correct statement.

$A$ parachutist,after bailing out,falls $20\,m$ without friction. When the parachute opens,it decelerates at $2\,m/s^2$. He reaches the ground with a speed of $4\,m/s$. At what height did he bail out (in $,m$)?