Answer
The kinetic energy is $~~5.6~J$
Work Step by Step
We can find the kinetic energy $K_2$:
$K_2+U_{e2} = K_1+U_{e1}+W$
$K_2 = 0+U_{e1}-U_{e2}+W$
$K_2 = \frac{1}{2}k~(x_1^2-x_2^2)-F~\Delta x$
$K_2 = \frac{1}{2}(4000~N/m)~[(0.10~m)^2-(0.080~m)^2]-(80~N)(0.020~m)$
$K_2 = 5.6~J$
The kinetic energy is $~~5.6~J$
