2.3 Gravitational Force

What is Gravity?

Gravitational force is one of the four fundamental forces of nature. It's the attractive force between two objects with mass (massive objects). Newton’s Law of Universal Gravity gives an equation for the gravitational force.

From this equation, you can see that as 2 objects increase in mass, the stronger the gravitational force will be. Also, if the distance between the 2 masses increases, the force will decrease by a square of that factor.

Unless stated otherwise, all problems in AP Physics 1 problems will take place on Earth. Near Earth, the acceleration due to gravity has been calculated as ${g\approx9.81\frac{m}{s^2}}$. Using Newton’s Law of Universal Gravity, we get that ${g=G\frac{M}{r^2}}$. This allows us to get that ${F_g=mg}$ for problems with an object near Earth.