I was wondering, how can both a proton and a neutron weight 1u?
An Up quark has a mass of 1.7–3.1 MeV (according to Wikipedia).
Down has a mass of 4.1-5.7 MeV.
Average Up: 2.4
Average Down: 4.9
If a proton is Up+Up+Down (2.4+2.4+4.9) it has a mass of 9.7 MeV.
A neutron is Down+Down+Up...