The electric eye that prevents an elevator door from closing when you are in the doorway relies upon which physics principle? more than one may apply to this question -special relativity -atomic spectra -photoelectric effect -radioactivity

"why is graphite used instead of gold or copper wires to conduct electricity in very hot situations such as an industrial kiln? " that's the question, but the thing is, i don't even understand what an "industrial kiln" xd assistance would be < 3

This question is worth 54 points ! rock falls from a ledge to the ground what energy conversion occurs during this process a potential to kinetic b kinetic to potential c thermal to mechanical d chemical to mechanical

Why do different substances have diffrent properties