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**1. Homework Statement**

What is the kinetic energy given to the proton in the decay of a neutron when:

a) The electron has negligibly small kinetic energy

b) The neutrino has negligibly small kinetic energy

**2. Homework Equations**

Q = (m

_{n}- m

_{p}- m

_{e}- m

_{v}) c

^{2}= .782MeV

Where T is kinetic energy, and the neutron is at rest:

Q = T

_{p}+ T

_{e}+ T

_{v}

**3. The Attempt at a Solution**

Now my thoughts are similar for both part a) and b):

For a,

if the electron has zero kinetic energy, then by conservation of momentum, the proton and the neutrino must have equal and opposite momentums. But from lecture, my professor explicitly wrote:

Since m

_{p}>> m

_{e}, and m

_{p}>> m

_{v},

T

_{p}<< T

_{e}, and T

_{p}<< T

_{v}, so the Q value is practically

shared between the electron and the neutrino.

and when T

_{v}= 0, T

_{e}= Q

So is this a trick question then? Is the kinetic energy given to the proton always going to be essentially zero in part a) and b) , since it is so massive?