Strong nuclear force

Inside an atom’s nucleus, the protons are all positively charged, so they repel each other due to the electrostatic force.

Holding them back together again is a force called the strong nuclear force, keeping the nucleus stable. It acts between the protons and the neutron.

Range

• The strong nuclear force is really strong, but it only works over very short distances (about the size of a nucleus).
• It’s only got a range of about 3\times10^{-15} meters. That means it only works when the protons and neutrons are really close together, like inside the nucleus.

Repulsion

• If the protons get too close together, though, the force acts completely differently.
• Instead of attracting them, it starts to repel them.
• That might seem like it could cause the nucleus to fly apart, but it actually helps to keep the nucleus stable by preventing the protons from getting way too close to each other.