Foucault’s Pendulum is one example of the Coriolis effect, which is one of the pieces of evidence that suggests that the Earth revolves around its own axis. It does not show that the Earth rotates around the Sun. Another piece of evidence is the fact that we see the stars go round us every 24 hours, which Flat Earthers counter by saying that the Earth is stationary and the stars rotate around us.
Mach’s principle is a vaguely-stated hypothesis rather than a law. Mach was considering whether rotation is relative or absolute. Straight-line motion is thought to be relative: if you are moving with a certain velocity relative to me in a straight line ... Read even more
