Consider a rock on a turntable going around in circles. The coefficient of static friction between the rock and the turntable surface is so high that the rock never slips. Is the mechanical energy of the rock conserved?

1. Yes--there are no nonconservative forces present.
2. Yes--nonconservative forces are present but do no work.
3. Yes--nonconservative forces are present and do work, but the work done by some exactly cancels the work done by others.
4. No, mechanical energy is not conserved.