•What
holds protons in the nuclei of atoms?
–Coulomb
(electric) repulsion should make protons fly apart
•They
are packed so close together – must have very strong force to hold them
–Nuclear
“Strong
force”
attracts nucleons (protons, neutrons)
–
•Why
doesn’t strong force collapse all atoms into a giant nucleus?
–Nuclear
Strong force is very short range
•falls
off quickly after a few proton radii
–Coulomb
force is long range
•falling
off only as 1/r2
•At
large distances only coulomb force is important Þ repulsion
•Nuclear
Strong Force important only close together
–Requires
very high speed (high temperature) collision for fusion
•