Two children are being pulled on a sled (40.0 kg total mass) by a rope that supplies a 150 N horizontal force and a 100 N upward force. If the sled moves
across the ground at a constant velocity, calculate the coefficient of friction for the
surfaces involved.

It is d, all the other ones say incorrect answer .

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.