Modern physics question

1. Feb 3, 2005

mike217

The free neutron is known to decay into a proton, an electron, and an antineutrino v' (of negligible rest mass) according to n-->p+e+v'. The decay products are measured to have a total kinetic energy of 0.781+/-0.005 MeV. Show that this observation is consistent with the excess energy predicted by Einstein's mass-energy relationship.

Doing this problem I get: (Mn-Mp-Me)c^2=(940 MeV/c^2-938 MeV/c^2-0.511 MeV/c^2)c^2=1.489 MeV which is not equal to the change in kinetic energy 0.781+/-0.005 MeV

2. Feb 3, 2005