What is the gravitational force between the earth and a body called?

$A$ boy on a cliff $49\, m$ high drops a stone. One second later,he throws a second stone after the first. They both hit the ground at the same time. With what speed did he throw the second stone?

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

$A$ boy is whirling a stone tied with a string in a horizontal circular path. If the string breaks,the stone

State any one phenomenon related to the universal law of gravitation.

State the source of centripetal force that our earth requires to revolve around the sun. List the factors on which this force depends.