Question:
(a) In a quark model of elementary particles, a neutron is made of one up quarks and two down quarks. Assume that they have a triangle configuration with side length of the order of 10-15 m. Calculate the electrostatic potential energy of neutron and compare it with its mass 939 MeV.
(b) Repeat above exercise for a proton which is made of two up and one down quark.
Solution:
There are three charges in the system. The potential energy of the system is equal to the sum of the PE of each pair.
U = 1/4 π ε0 {qdqd/r – quqd/r – quqd/r}
Substituting the values we get,
U = 5.11 10-4