We know that the universal law of gravitation was put forth by Sir Isaac Newton in 1687. It is one of the most important laws of physics. Let us know more about Newton’s universal law of gravitation and gravitational constant.
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Universal Law Of Gravitation
According to Newton’s Universal Law of Gravitation, the force exerted between two objects by each other is given by the following relation.
where g is the gravitational force between two bodies, m1 is the mass of one object, m2 is the mass of the second object and r is the distance between the centres of two objects.
Gravitational Constant
The actual force exerted between two bodies can be given by the following equation
where G is the universal gravitational constant with a value (G = 6.674 × 10-11 N · (m/kg)^{2}). G here is an empirical constant of proportionality.
What is interesting here is that, even though it is Newton’s Universal Law of Gravitation, the value of G wasn’t given by him. This was calculated by Henry Cavendish in 1798 through a series of experiments and observations. The influence of the earth’s core on the experiments is hypothesised to alter its rotational inertia, because of which the value of G given is not always constant throughout the globe.
Another theory regarding the universal gravitational constant (fun fact: it is also referred to as Big G) is that, if it is true that the universe is expanding since the Big Bang, then the value of G will keep decreasing!
The universal gravitational constant is used in Newton’s Universal Law of Gravitation, Einstein’s General Theory of Relativity and also Kepler’s Third Law of Planetary Motion to calculate the time period of a planet to complete one full revolution in its orbit.
To know about the history of gravitation watch this video
Frequently Asked Questions – FAQs
What is gravity?
State Newton’s Law of Universal Gravitation.
Newton’s Law of Universal Gravitation states that every particle attracts every other particle in the universe with force directly proportional to the product of the masses and inversely proportional to the square of the distance between them.
State true or false: Force of attraction exists between the other planets and the sun.
According to Newton’s Universal Law of Gravitation, the force exerted between two objects is given by which formula?
What is the value of the universal gravitational constant (G)?
Watch the full summary of the chapter Gravitation Class 9
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