The ∑⁺ (mass 1189 MeV/c²) is composed of two up quarks (u) and one strange quark (s). The mass of an up quark is about 4 MeV/c², and the mass of a strange quark is about 150 MeV/c². Why don’t these mass values “add up” to equal the mass of the ∑⁺ as one might expect? Does the mass of the  ∑⁺ come mainly from the masses of these quarks or from the potential energy associated with binding? Explain.