A5000-kg spacecraft is in a circular orbit 2000 km above the surface of mars. how much work must the spacecraft engines perform to move the spacecraft to a circular orbit that is 4000 km above the surface? assume the mars radius is 3.4 \times 10^6 m3.4×10 6 m and the mass of mars is  6.4 \times 10^{23}6.4×10 23  kg. (express your answer in the format: 1.23 \times 10^{10} j1.23×10 10 j as "1.23e10 j".)

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.