Newton's Law of Gravitation:
Statement: According to this law, when two mass bodies are separated at finite distance then there must be an attractive force experience by them which is directly proportional to the product of their masses and inversely proportional to the square of their separation.
Consider two mass bodies m1 & m2 be kept at distance d. Then the force of attraction F is given as
Now, from above equations, we have
or,
Here is the universal gravitational constant.