A plate falls to the floor. When is its potential energy the lowest?
1.in mid-fall
2.Immediately after it begins to fall
3.When its kinetic energy is the highest
4.Before it falls

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.

Which is an example of gaining a static charge by conduction? a) rubbing a balloon against your hair. b) shuffling your shoes across a carpet. c) bringing a charged rod near an electroscope. d) touching your car on a cold day and getting a shock.

An isotope undergoes radioactive decay by emitting radiation that has a –1 charge. what other characteristic does the radiation have?