Why is it that an object can accelerate at a constant speed but not at a constatnt velocity

An object can accelerate while traveling at constant speed but not at constant velocity. This is because acceleration is a measure of the change in velocity over time. Speed is a scalar quantity with magnitude but not direction while velocity is a vector quantity with both magnitude and direction.

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.