Question

In the nucleus of helium if f1 is the net force between two protons f2 is the net force betwwen in the neutrons and f3 is the net force between in the protorn and neutrons then

Answer 1

Protons inside a nucleus are bound to each other via the Strong Nuclear Force (residual) carried by the Gluons (actual, inside a baryon), or by Mesonic exchange (residual, outside a baryon, here within the nucleus). This is the strongest of the four fundamental forces. That's why they stay there against their repulsive forces. But for the strong nuclear force to operate, there is one condition to be satisfied. This is the distance threshold. It is a range of 0.8×10−15to4.2×10−15m0.8×10−15to4.2×10−15m for the strong nuclear force. So the protons too exist together (stably) within a similar range.