Fundamental Forces

The 4 Fundamental Forces in Nature

1. Gravity
2. The Weak Force
3. Electromagnetism
4. The Strong Force

Gravity

• Gravity is an attractive force that occurs between two objects that have either mass or energy
• Gravity is the weakest of the four forces and is significant only between massive objects (cosmic scale)
• Newton's Law of Gravitation is described by the following equation:

• Due to the denominator (r2), gravity becomes increasingly smaller the further apart the objects are
• The constant G is equal to $\frac{6.67408*10^{-11}m^3}{kgs^2}$ which can only create a significant force at extremely large masses

Electromagnetism

• Electromagnetism is responsible for the attraction or repulsion of charged particles
• This force has a very similar equation to gravity and is known as Coulomb's Law:

The Strong Force

• The strong force is responsible for holding nuclei of atoms together - that is keeping the protons and neutrons "attached" to each other and is the strongest force in the universe
• It is much stronger than the electromagnetic force which is why it can hold together protons at such a close distance (if there were no strong force protons would fly away from each other due to similarly charged particles repelling each other)
• Only extends as far as the width of a proton
• Can be thought of as velcro
• When velcro is attached it is very strong but as soon as it is separated a far enough distance there is no strength whatsoever

The Weak Force (AKA the Weak Nuclear Interaction)

• The weak force is responsible for particle decay (radioactive decay, beta decay)
• Change of one sub-atomic particle (neutron, proton, electron) into another
• The Weak force is only apparent at an even smaller distance than the strong force (roughly 1/1000 diameter of a proton)