the principle of the conservation of energy
that work done by a force is equivalent to a transfer of energy
that energy transfers can be represented on a Sankey diagram
that work W done on a body by a constant force depends on the component of the force along the line of displacement as given by W = Fs cos θ
that work done by the resultant force on a system is equal to the change in the energy of the system
that mechanical energy is the sum of kinetic energy, gravitational potential energy and elastic potential energy
that in the absence of frictional, resistive forces, the total mechanical energy of a system is conserved
that if mechanical energy is conserved, work is the amount of energy transformed between different forms of mechanical energy in a system, such as kinetic, gravitational potential, and elastic potential
that power developed P is the rate of work done, or the rate of energy transfer
efficiency η in terms of energy transfer or power
energy density of the fuel sources.