Fundamental means something that is basic, unique, and not made by anything else; something that is used to make other things. A force is a push or a pull. A fundamental force is the most basic kind of force; a kind of force that is unique and not made up of any other forces and is used to make different forces. There are four fundamental forces in the universe, but to make things simple, we will only talk about three of them in this class (extra information about the fourth is available at the bottom of the page). These forces each have different effects and different strengths.


Gravity is the first of the fundamental forces and probably the one you are most familiar with. Gravity is what keeps us down, what makes things fall. It keeps the planets in their orbits around the sun and is responsible for the nuclear fusion in the sun that provides us with all our energy on earth. Gravity affects both matter and light and it is caused by mass (remember that mass is a property of matter that describes how much matter there is). Gravity is also what gives us weight and is only a pulling, or attractive, force. It is the weakest of the fundamental forces, but is the most persistent and acts on the biggest scale. Planets, stars, and galaxies are all ruled by gravity.


Electromagnetism is the second fundamental force. You may have heard of it before in physics. It is the combination of the electric force (electricity) and the magnetic force (magnetism). The reason that electricity and magnetism can be combined and that they are not fundamental is because you can turn electricity into magnetism and magnetism into electricity. Electromagnetism is also responsible for light and chemical bonds. It is the electromagnetic force that holds atoms and molecules together; it's the force that keeps you falling through your chair. Since it can do that, we can tell that it is stronger than gravity. That means that electromagnetism is the second strongest force (that might not sound like much, but think about how hard it is to pull a spoon apart compared to how easy it is to pick a spoon up). Electromagnetism is both an attractive (pulling) and a repulsive (pushing) force.

Strong Nuclear

The strong nuclear force is the third fundamental force. You probably haven't heard of it before, but it is the force that holds the nucleus of the atom together. The strong nuclear force is an attractive (pulling) force. The nuclear force is the strongest fundamental force, so strong that it can overpower the electromagnetic force. How else are protons prevented from flying apart in the nucleus? On the other hand, the strong force is very limited in its range. It can only work inside the nucleus of an atom, unlike electromagnetism and gravity which are both infinite in range. Once you start talking about distances greater than the nucleus of an atom, the strong force no longer exists.

Extra Information -- Weak Nuclear

This section will not be on the test; its only here in case you are curious. The weak nuclear force might seem similar to the strong nuclear force, but is actually more closely related to the electromagnetic force. The weak nuclear force acts on sub-atomic particles such as protons, neutrons, and electrons and is responsible for radiation. The weak nuclear force has the ability to change one kind of particle into another in certain cases, and that results in radiation. The weak nuclear force is generally considered a repulsive force and is a little stronger than gravity but weaker than the other forces. Like the electromagnetic force, it deals with positive and negative charges but these charges are not the same kind as the electromagnetic force. All-in-all, it's a very weird force. As I said, it will not be on the test.