Answer:
Revolution of moon around the earth
Explanation:
The revolution of moon around the earth.
The gravitational force acting on the moon is balanced by the centripetal force acting on the moon.
Gravitational force of earth on moon is given by

where, M be the mass of earth, m be the mass of moon and r be the distance between moon and earth.
The centripetal force acting on moon is

These two forces balance each other and then the moon revolves around the earth in fixed orbit.