Question

Write the formula to find the magnitude of the gravitational force between the earth and an object on the surface of earth.

Answer 1

1. Let M be the mass of the earth and m be the mass of the object on the surface of the earth. As the object is very small as compared to the size of the earth, the distance between them can be considered as the radius of the earth which can be represented by the symbol R.
2. Let F be the magnitude of the gravitational force between the earth and the object, which according to Newton's universal law of gravitation, the gravitational force is directly proportional to the product of M and m, and inversely proportional to the square of R.
3. The formula for F can be written as: $F=\frac{GMm}{R^2}$, where G is the called universal gravitational constant.

Thus, the formula to find the magnitude of the gravitational force between the earth and an object on the surface of the earth is $F=\frac{GMm}{R^2}$.