. Let us say that you put a cup of cold water in one room and a cup of hot water in another room. Both rooms are at room-temperature. Why does the cold water get
warmer and the hot water get cooler?

What is the single most important equation in all of physics?

A1500 w electric heater is plugged into the outlet of a 120 v circuit that has a 20 a circuit breaker. you plug an electric hair dryer into the same outlet. the hair dryer has power settings of 600 w, 900 w , 1200 w, and 1500 w. you start with the hair dryer on the 600 w setting and increase the power setting until the circuit breaker trips. under what setting does the circuit breaker trip.

Is a volume of space that is empty of matter.