An atomic nucleus consists of positively charged protons and neutral neutrons, so the electrostatic repulsion should destroy it by making the protons fly apart. This doesn't happen because: (a) The strong force is ~100 times stronger than electromagnetism.
(b) The weak force generates massive particles that hold it together.
(c) Electromagnetism is sometimes attractive.
(d) Gravity is always attractive.

Video Transcript

This is College Physics Answers with Shaun Dychko. The protons that are in a nucleus have a very strong coulomb repulsion between them and if nothing else was there to compensate, the nucleus would fly apart. But there is something there and that is the strong force and the strong force is about a 100 times stronger than the electrostatic repulsion. So that means the nucleus stays together as a result of the strong force. The answer is (a).