Awave travels down the length of a 25-meter rope in 5.0 seconds. the speed of the wave is
5.0 m/s
0.2 m/s
125 m/s
25 m/s

The answer is 5.0 m/s. It is asking for the SPEED of the wave, therefore, you need to know that speed = distance / time. You just simply divide 25 meters (distance) to 5.0 seconds (time) which will leave you the speed of 5.0 m/s. 

Tell me the answers for your question and you!

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.