**THE GRAVITATIONAL FORCE**

** What is gravitational force? Mention its important properties. Give some examples of gravitational force.
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** Gravitational force is the force of mutual attraction between two bodies by virtue of their masses. It is a universal force. Every body attracts every other body of the universe with this force. According to Newton’s law of gravitation, the gravitational attraction between two bodies of masses m1 & m _{2 }and separated by distance r is given by**

** where G is the universal gravitational constant which is equal to 6.67 * 10^ -11 Nm^2/Kg^2.**

**Important properties of gravitational force:**

**It is a universal attractive force.****It is directly proportional to the product of the masses of the two bodies.**

**It obeys inverse square law.****It is a long range force and does not need any intervening medium for its operation.****Gravitational force between two bodies does not depend upon the presence of other bodies.**

**It is the weakest force known in nature.****It is a central force (i.e., it acts along the line joining the centres of the two bodies).****It is a conservative force (i.e., work done in moving a body against the gravitational force is path independent).****Gravitational- force between two bodies is thought to be caused by ah exchange of a particle called graviton.**

**Examples of gravitational force:
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**‘ 1. All bodies fall because of the gravitational force of attraction exerted on them by the earth.**