Which best describes why heat pumps are reversible? O They can heat and cool an indoor space.
O They involve a metal expanding or contracting against another.
They combust and can also add coolant.
They allow a piston to move up and down.

Match the atomic particles with their characteristics. 1. made of two protons and two neutrons neutron 2. similar to an electron; positive charge neutrino 3. orbits nucleus; negative charge positron 4. bundle of energy; zero charge proton 5. found in nucleus; positive charge meson 6. very unstable; +, -, or zero charge gamma 7. found in nucleus; zero charge electron 8. negative particle; negative charge beta 9. atomic energy converted to mass alpha

Wavelength of 125 meters is moving at a speed of 10 m/s. what is it's frequency?

The diagram shows a boulder rolling down a hill into a valley and then up the opposite hill. at which position does the boulder have the greatest kinetic energy? ab c d