De Broglie wave length, average electron energy and momentum calculation

[orangeincup]

Homework Statement

Calculate the average electron energy of an electron in an electron gas at thermal equilibrium. Temperature is 315K. Calculate the average electron momentum. Calculate the de Broglie wave length of the electron

Homework Equations

3*kT/2

The Attempt at a Solution

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Part 1) 3*(8.62*10^-5)*315K/2 = .0402 eV

Part 2) I'm unsure of how to calculate average momentum. Should I use the mass of the electron?

 

[TSny]

Hint: Momentum is a vector quantity.