Example: Electric Force

Question:

What is the magnitude of the repulsive electrostatic force between two protons in an atomic nucleus. The distance between nuclear protons is about 10^-15 m.

Answer:

Given: r = 10^-15 m, q₁ = q₂ = 1.6·10^-19 C
Find: F
Use Coulomb's Law:
The force is repulsive, because the two protons have the same sign of charge.
Since the nucleus does not fly apart, there must be an even greater force acting to keep the nucleons together (the Strong Nuclear force, about which we will learn later, during the last week of this semester).