In your own words, explain why sound waves cannot travel in space.

In order for sound to travel, it has to have its medium. The medium, which are particles or molecules of solid, liquid or gas, collides with each other, it vibrates thus creating sound. In space, there are no particles or molecules that will vibrate for sound to be made.

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.