Calculate Energy of Neutron Wavelength 0.1nm

[bon]

Homework Statement

Calculate the energy of a neutron wavelength 0.1nm

Homework Equations

The Attempt at a Solution

let L = lambda

So i just use E = hv/L

L = hv/E

But how do i write v in terms of E? isn't E the total energy rather than just kinetic...

 

[bon]

Or can i use lambda = h/p, work out the KE, then add on the rest energy?