Binding energy is a measure of how much work must be done against nuclear forces in order to disassemble a nucleus into its constituent parts. For example, the amount of energy in order to disassemble He into 2 protons and 2 neutrons requires 28.3 MeV of work to be done on the nuclear particles. Describe the force that makes it so difficult to pull a nucleus apart. Would it be accurate to say that the electric force plays a role in the forces within a nucleus? Explain why or why not.

Video Transcript

This is College Physics Answers with Shaun Dychko. It takes 28.3 megaelectron volts of work to disassemble a helium nucleus into its constituent— protons and neutrons. So what force makes it so difficult to pull the nucleus apart and is it accurate to say that the electric force plays a role in the nucleus? So the strong nuclear force is an attractive force operating over a very short range and it's responsible for gluing the nucleus together. The electric force doesn't matter for small nuclei because the strong nuclear force overcomes the electrical repulsion between protons but for large nuclides, the electric force is important because it still repels over the large distance of a large nuclide whereas the strong nuclear force can't operate over such a large distance so if this is a proton on this side of a large nucleus and this is another proton on the other side, they will repel each other and there's no compensating attraction due to the strong nuclear force since they are separated so far. So the electric force makes large nuclei unstable.