A mother (mass 60.0 kg) skates across an ice rink with negligible friction toward her child (mass 20.0 kg), who is standing still on the ice. If the mother moves at 4.0 m/s before she picks up her child, what is her new speed after she picks up her child and holds onto him

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 statement correctly describes a step-up transformer? a. it increases the amount of electric energy available. b. it increases the voltage of an electric current. c. it changes direct current into alternating current. d. it has more loops of wire in its primary coil.

Which is the best predictor of the radioactive nature of an isotope? o the proton-to-electron ratio the neutron-to-proton ratio o the neutron-to-electron ratio the electron-to-proton ratio