**1. The problem statement, all variables and given/known data**

As the result of the weak interaction a neutron recomposes to a proton and an electron. Could the electron exist inside the neutron? Assume that the radius of the neutron is [itex]10^{-15}m[/itex].

**2. Relevant equations**

[tex] \Delta p =\frac{h}{2\pi \Delta x} [/tex]

[tex]E=\frac{p^2}{2m}[/tex]

**3. The attempt at a solution**

The book shows an equation as the solution of the exercise:

[tex]E=\frac{p^2}{2m (\Delta x)^2}\approx 1,5\cdot 10^{-19} J[/tex]

I just can not understand how the [itex](\Delta x)^2[/itex] got into the denominator of the fraction.

http://ift.tt/1g1Yqqq