"completely stable nucleus" question The nucleus of a helium isotope contains 2 protons. I have just worked out the magnitudes of the electrostatic force and the gravitational attraction between the 2 protons. The question now reads "the nucleus is completely stable. Considering the magnitudes of the forces [the previous questions], what conclusions can you draw about the forces that are holding the nucleus together?" My initial thoughts on reading the question before doing the math was that the forces would turn out to be equal, otherwise the nucleus would fall apart. I then realised that the electostatic force is always much more powerful than the gravitational one, which was the case when I worked out the magnitudes. So, that leaves me wondering... 1. Why isn't the nucleus ripped apart, as the forces pulling it apart are many times stronger than the ones holding it together? 2. What exactly does "completely stable" mean? 3. What conclusions can be drawn from the magnitudes of the forces? 4. The question also mentions that there is a single neutron in the nucleus - does this have anything to do with it? Thank you in advance.