mgzg_{c}PE mgzg_{c}50 lbm132.17 ftsec^{2}10 ft1lbf sec^{2}32.17 lbmftKEmv^{2}2g_{c}ENERGY AND WORKEnergy, Work, and PowerCP-05 Page 2Rev. 0As an example, consider the energy stored in hydrogen and oxygen as potential energy to bereleased on burning. Burning changes their relative separation distance from the elemental formto the compound form as water releases the potential energy.When discussing mechanical potential energy, we look at the position of an object. Themeasure of an object's position is its vertical distance above a reference point. The referencepoint is normally the earth's surface, but can it be any point. The potential energy of the objectrepresents the work required to elevate the object to that position from the reference point.Potential energy is mathematically represented by Equation 5-1.PE = work to elevate = weight x height (5-1)where:PE=potential energy in ft-lbfm=mass in lbmg=32.17 ft/sec^{2}g=32.17 (lbm-ft)/(lbf-sec )c2z=height above a reference in ftIt should be noted the g is used only when using the English system of measurement.cExample:What is the potential energy of a 50 lbm object suspended 10 feet above theground?Answer:PE = 500 ft-lbfKineticEnergyKinetic energy is defined as the energy stored in an object because of its motion. If you havea baseball in your hand, it has no kinetic energy because it is not moving. But if you throw theball, your hand has provided energy to give the ball motion. When you release the ball, it leavesyour hand at some velocity. The energy you have given the ball will determine the velocity ofthe ball. Because the kinetic energy is due to the motion of the object, and motion is measuredby velocity, kinetic energy can be calculated in terms of its velocity, as shown below.(5-2)