$A$ particle is thrown vertically upwards with a velocity of $4\,ms^{-1}$. The ratio of its accelerations after $1\,s$ and $2\,s$ of its motion is

$A$ body thrown vertically upwards from the ground reaches a maximum height $H$. The ratio of the velocities of the body at heights $\frac{3H}{4}$ and $\frac{8H}{9}$ from the ground is

$A$ ball projected up passes the same height $H$ at $2 \,s$ and $10 \,s$. The value of $H$ is [Use $g=9.8 \,m/s^2$]. (in $m$)

An object is thrown vertically upwards. At its maximum height,which of the following quantities becomes zero?

$A$ boy is standing on top of a tower of height $85 \, m$ and throws a ball in the vertically upward direction with a certain speed. If $5.25 \, s$ later he hears the ball hitting the ground,then the speed with which the boy threw the ball is .......... $m/s$ (take $g = 10 \, m/s^2$ and speed of sound in air $= 340 \, m/s$).

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 $g = 10 \, m/s^2$)