3. A solar greenhouse has three twenty-lb (pound) steel barrels as thermal storage. The volume of the barrels is 55 gallons. The owner filled the first one barrel with 55 gallons of water, filled the second half full (27.5 gallons), and left the third empty. If the sun adds 500 BTUS of heat to each barrel, how much will each barrel warm up? A gallon of water weighs 8.34 lb, and a gallon in volume is equal to 0.13368 ft. (9 points) Air Water Steel Specific heat (Btu/lb-F) 0.24 1 0.12 density (lb/ft) 0.075 62.0 489.0