Nuclear forces.

We know that the nucleus consists of protons and neutrons.Due to the positive charge on proton, there Wii be a repulsive electrostatic force between the two protons and the resulting repulsive force between protons will tend to push the nucleus apart.Therefore, for the nucleus to have a permanent existence, there must be some strong attractive forces between protons and neutrons inside the nucleus.These attractive forces cannot be gravitational because they are much smaller than the attractive force demanded.Moreover, these forces cannot be electrical in nature because the strong repulsive forces between protons will lead to distruption of nucleus. Actually these forces are short range attractive forces known as nuclear forces.