Need help on uncertainty principle

[s-saber148]

Homework Statement

In order for a neutron can exist in a nucleus, its wavelength must be smaller than the size of the nucleus (say 2 x 10-15 m)
Use the uncertainty principle to calculate and show that a neutron would have a kinetic energy much smaller than its rest mass energy

Homework Equations

ΔE Δt > h/4π

The Attempt at a Solution

I had no clue in how to solve this problem. At first, I was thinking to solve for E, but figured that I don't know how to calculate for t.

Can anyone help me with this question?

 

[Redbelly98]

There's another version of the uncertainty principle, involving position and momentum. Try that.

p.s. welcome to PF.