## SAT Physics Subject Test

**Chapter 3 ****Newton’s Laws**

**NEWTON’S LAW OF GRAVITATION**

Newton put forth another important theory about the Universe: Any two objects in the Universe exert an attractive force on each other—called the **gravitational force**—whose strength is proportional to the product of the objects’ masses and inversely proportional to the square of the distance between them. If we let *G* be the **universal gravitational constant**, which is equal to 6.67 × 10^{-11} **N** • m^{2}/kg^{2}, then the strength of the gravitational force is given by the equation

The forces **F**_{1-on-2} and **F**_{2-on-1} act along the line that joins the bodies and form an action/reaction pair.