5. Which of these is necessary for electricity to flow? O The circuit must be closed.
O The circuit must be open.

What property is a characteristic of a substance that can be observed and does not change the identity of the substance

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

A2-kg bowling ball is 2.5 meters off the ground on a post when it falls. just before it reaches the ground, it is traveling 7 m/s. assuming that there is no air resistance, which statement is true?