The law of gravitation was discovered by Sir Issac Newton, a british mathematician, in the year 1665. Newton’s law states that every body in this universe attracts every other body with a force which is directly proportional to the product of the masses of the two bodies and inversely proportional to the square of the distance between their centres.
According to this law, if m1 and m2 are two point masses sepearted by a distance of r, then the gravitational force between them will have magnitude ‘F’ given as
Here, the proportionality constant ‘G’ is called the universal gravitational constant. The value of G is determined by the British scientist Henry Cavendish in 1798 and it is equal to 6.67×10-11 N–m2Kg-2. The dimensions of G are [M-1L3T-3].
The value of G is a universal constant which has same value every where irrespective of time, space and physical or chemical conditions. G is a scalar quantity. Because G is a universal constant, Newton’s law of gravitation is also called universal law of gravittation.
