Definition: Gravitation
"Every particle of matter in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The direction of the force is along the line joining the particles."
or
The force by which the Earth attracts objects towards its centre is called gravitational force.
Definition: Universal Law of Gravitation
"Every particle of matter attracts every other particle of matter with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them."
Definition: Potential Energy
"Potential energy is the work done against conservative force (or forces) in achieving a certain position or configuration of a given system."
OR
The energy stored in an object because of its position or state is called potential energy.
Answer the following question in detail.
What is a critical velocity?
The exact horizontal velocity of projection that must be given to a satellite at a certain height so that it can revolve in a circular orbit round the Earth is called the critical velocity or orbital velocity (vc).
Definition: Satellite
The objects that revolve around the Earth are called Earth satellites.

Answer the following question.
Define the binding energy of a satellite.
The minimum energy required by a satellite to escape from Earth’s gravitational influence is the binding energy of the satellite.
Definition: Binding Energy of Satellite
"The minimum energy required by a satellite to escape from Earth’s gravitational influence is the binding energy of the satellite."
Definition: Escape velocity
"The minimum velocity with which a body should be thrown vertically upwards from the surface of the Earth so that it escapes the Earth’s gravitational field, is called the escape velocity (ve) of the body."