The rate of energy change or transfer is called power (P) and can be mathematically represented by P = ΔE/Δt or P = W/Δt. Power is a scalar property. The unit of power is the watt (W), which is equivalent to one Joule of energy transferred in one second (J/s).
Work can be calculated for situations in which the force and the displacement are at angles to one another using the equation W = FΔx(cosθ) where W is the work, F is the force, Δx is the displacement, and θ is the angle between the force and he displacement. This means when the force and the displacement are at right angles, no work is done and no energy is transferred between the objects. Such is the case for circular motion.