Molecules in air in the atmoshpere are attracted by gravitational force of the earth. Explain why all of them do not fall into the earth just like an apple falling from a tree.

The earth and the moon are attracted to each other by gravitational force. Does the earth attracts the moon with a force that is greater than or smaller than or the same as the force with which the moon attracts the earth ? Why ?

A rain drop of radius 2 mm falls from a height of 500 nr above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey ? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 m s^-1 ?

Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object ?

Explain why an apple should fall down to meet the earth instaed of earth moving upwards to meet the apple, when the gravitational pull is the same in both cases.