recoverable internal strain energyrecoveryrecovery cyclerecovery of velocity headrecovery testrecreation lakerecreational arearecreational triprectangularrectangular cross sectionrectangular loaded arearectangular moment of inertiarectangular rigid framerectangular sectionrectangular stress diagramrectangular weirrectificationrectifierrectilinearrectilinear translationrectilinear trendrecuperation periodrecurrence formularecurrence intervalrecurrence relationred clayred leadred lead puttyred mudredbrickredistributionredistribution of forceredistribution of stressredressingreduced matrixreduced modulus of elasticityreduced plastic momentreduced pressurereduced spanreduced stiffnessreduced temperaturereducerreducing elbowreducing teereducing tee piecereductionreduction coefficientreduction factorreduction in areareduction in sectional area