$A$ stone dropped from a certain height takes $4$ seconds to reach the ground. The height is: (in $, m$)

Show that if the earth attracts two bodies $A$ and $B$ placed at the same distance from the centre of the earth with the same force,then their masses are equal.

State whether the following statement is True or False:
All objects attract each other along the line joining their centre of mass.

If gravitation is the power by which all bodies tend towards each other,then why do all bodies tend towards the centre of the earth?

Is it possible to shield a body from a gravitational field?

$A$ ball is thrown up and attains a maximum height of $100 \, m$. It is thrown upwards with a speed of: (in $, m/s$)