A sound wave travels through air. In which regions of the wave are air molecules the least dense? *

A. compressions
B. crests
C. rarefactions
D. troughs

The objects are acted upon by only one force. gravity. mass times the acceleration of gravity (-9.81meters/second squared).

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.