Page 3 - Simplied Force

SIMPLIFIED COURSE ON SEE SCIENCE : CHAPTER- FORCE

Newton’s Universal law of gravitation

“Everybody in this universe attracts everyanother body with a force which is (i) directly
proportional to the product of their masses and (ii) inversely proportional to the square of the
distance between their centers”.
Universal gravitational constant ‘G’

Universal gravitational constant ‘G’ can be defined as the force of gravitation that is exerted
between two unit masses, separated from one another by a unit distance.

The SI unit of G is Nm kg .
2
-2
The approximate value of G is 6.67 X 10 Nm kg .
-2
2
-11
Properties of G
i. The value of G is independent of the nature and chemical composition of the masses of the bodies,
and the medium in which the bodies are occurred.
ii. The value of G is unaffected by temperature and pressure.

Variation of Force of Gravitation with mass and distance

Consequences of gravitational force
i. The presence of solar system and planets revolve round the sun due to the presence of gravitational
force.
ii. The presence of atmosphere on the earth is due to the gravitational force.
iii. The gravitational force of the earth keeps us firmly on the surface of the earth.
iv. Tides in seas and oceans are due to the gravitational force of the sun and moon.

Special features of gravitational force
i. The gravitational forces between two bodies constitute on action and reaction pair.
ii. The gravitational force between two bodies does not depend upon the nature of the intervening
medium.
iii. The gravitational force between light bodies is extremely small and hence such smaller force is not
felt in practice. However, it becomes appreciable in case of massive bodies.

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