### Universal Law of GravitationEdit

*Explanation of Newton's Law of Universal Gravitation*

**Force of gravitation**, or Fg, refers to the force that attracts two massive objects to each other—**gravity**.

**m1**and**m2**are the separate masses attracted to each other by the**force of gravitation**.

- The variable
**r**stands for the distance between**m1**and**m2**.

- G is the universal gravitational constant. The universal gravitational constant is 6.67 x 10-11
- N=newtons
- m=meters
- kg=kilograms

As you can see in the visual above, the law of gravitation basically states that the force of gravitation is equal to the universal gravitational constant, multiplied by mass one and mass two, all divided by the distance between masses (squared).

As an example problem, let’s use these values:

- m1 = 2.6 x 102 kg
- m2 = 2.3 x 102 kg
- r = 1.2 x 102 m

According to this formula, Fg = (3.99 x 10^-6(n*m^2))/(1.2 x 10^2m)^2. When you simplify this completely, Fg = (2.77 x 10^-10).

This is the Law of Universal Gravitation as discovered by Isaac Newton. The basic idea is that everything in the universe that has any mass at all is attracted to each other by gravity—the “force of gravitation”. The Law of Universal Gravitation uses that idea in order to calculate the force of attracting gravitation using the mass, the distance between the two masses, and the universal gravitational constant, which is a value that is always the same across all time and space.

**References**

- http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html
- http://scienceworld.wolfram.com/physics/GravitationalConstant.html
- http://www.physchem.co.za/Motion/Gravity.htm
- Lazar, Miriam A. Let's Review: Physics, The Physical Setting. 3rd. North Babylon, NY: Barron's Educational Series, Inc., 2004.
- Zitzewitz, Paul W. Physics: Principles and Problems. New York, NY: Glencoe/McGraw-Hill, 2002.