Thermodynamics ENERGY, WORK, AND HEATIn most practical engineering calculations, the acceleration due to gravity (g) is numerically equalto the gravitational constant (gc); thus, the potential energy (PE) in foot-pounds-force isnumerically equal to the product of the mass (m) in pounds-mass times the height (z) in feetabove some reference level.Example:Determine the potential energy of 50 lbm of water in a storage tank 100 ft above theground.Solution:Using Equation 1-11PEmgzgcPE(50 lbm) (32.17 ft/sec2) (100 ft)32.17 ft lbm/lbf sec2PE5000 ft lbfKineticEnergyKinetic energy (KE) is the energy of motion. Using English system units, it is defined byEquation 1-12.(1-12)KEmv22gcwhere:KE = kinetic energy (ft-lbf)m = mass (lbm)v = velocity (ft/sec)gc= gravitational constant = 32.17 ft-lbm/lbf-sec2Rev. 0 Page 15 HT-01
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