A Level Physics Practice Exam 2025 - Free A Level Physics Practice Questions and Study Guide

The strong nuclear force is the fundamental force responsible for holding protons and neutrons together in an atomic nucleus. This force exhibits a unique behavior that is crucial for understanding nuclear interactions.

As particles such as protons and neutrons, which are held together by the strong force, move apart, the strength of the strong nuclear force actually decreases significantly. This weakening occurs at distances greater than about 1 femtometer (1 × 10^-15 m), which is approximately the size of a small atomic nucleus. At very close ranges, the strong force is exceptionally strong, providing the binding energy necessary to overcome the repulsive electromagnetic force between positively charged protons.

At distances beyond this range, the potential for the strong force to act diminishes rapidly, leading to a reduction in the attractive interactions between the nucleons. Therefore, as particles move further apart, the strong nuclear force not only weakens but can effectively become negligible beyond a certain distance, which contributes to the stability of atoms by preventing them from further separation and maintaining the integrity of the nucleus.

In summary, the correct understanding of the behavior of the strong nuclear force indicates that it indeed weakens as particles are separated, aligning with the answer provided.