Answer
$K_{Total} = 57.1 kJ$
Work Step by Step
To calculate the Total Translational Kinetic Energy of the conduction electrons, use the formula
$K_{Total} = NE_{Ave} = nvE_{Ave}$
Where,
$ E_{Ave} = (\frac{3}{5}) (7.00 eV) (1.602 \times 10^{-19} J/eV)$
From question,
$v = 1.00 \times 10^{-6} m^3$
$n = 8.43 \times 10^{28} m^{-3}$
Substitute all values into the Total Translation Kinetic Energy equation
$K_{Total} = (8.43 \times 10^{28} m^{-3})(1.00 \times 10^{-6} m^3)(\frac{3}{5}) (7.00 eV) (1.602 \times 10^{-19} J/eV)$
$K_{Total} = 5.71 \times 10^4 J$
$K_{Total} = 57.1 kJ$
