A 4.36 kg block free to move on a horizontal, frictionless surface is attached to one end of a light horizontal spring. The other end of the spring is fixed. The spring is compressed 0.144 m from equilibrium and is then released. The speed of the block is 1.18 m/s when it passes the equilibrium position of the spring. The same experiment is now repeated with the frictionless surface replaced by a surface for which uk = 0.340. Determine the speed of the block at the equilibrium position of the spring.

I thought I would use the formula K1=.5mv^2 and W=m*Fn*deltaX
Then do K1-W= K2, the take K2=.5mv^2 and solve for v to find the velocity but I got stuck on trying to find the variables for Work. Can you please help or find a different way to solve it?