$A$ stone is released from the top of a tower of height $19.6\, m$. Calculate its final velocity just before touching the ground. (in $, ms^{-1}$)

An object is thrown vertically upwards and rises to a height of $10 \, m$. Calculate:
$(i)$ the velocity with which the object was thrown upward and
$(ii)$ the time taken by the object to reach the highest point.

Write the expression for the acceleration due to gravity at the surface of the earth.

Two objects of different masses falling freely near the surface of the moon would:

Two objects of masses $m_1$ and $m_2$ having the same size are dropped simultaneously from heights $h_1$ and $h_2$ respectively. Find out the ratio of time they would take in reaching the ground. Will this ratio remain the same if $(i)$ one of the objects is hollow and the other one is solid and $(ii)$ both of them are hollow,size remaining the same in each case. Give reason.

$A$ ball is thrown vertically upward,acceleration due to gravity is: