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Tham khảo tài liệu 'aeronautical engineer data book episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fundamental dimensions and units 11 14.7 psi Rules of thumb An apple weighs about 1.5 newtons A meganewton is equivalent to about 100 tonnes An average car weighs about 15 kN Fig. 2.1 Pressure relationships X1000 Fig. 2.2 Pressure conversions 12 Aeronautical Engineer s Data Book 32 F 212 F Fig. 2.3 Temperature 2.3.6 Heat and work The basic unit for heat energy is the British thermal unit BTU . Specific heat energy is measured in BTU lb in SI it is joules per kilogram J kg . 1 J kg 0.429923 X 10-3 BTU lb Table 2.6 shows common conversions. Specific heat is measured in BTU lb F or in SI joules per kilogram kelvin J kg K . 1 BTU lb F 4186.798 J kg K 1 J kg K 0.238846 10-3 BTU lb F 1 kcal kg K 4186.8 J kg K Heat flowrate is also defined as power with the unit of BTU h or in SI in watts W . 1 BTU h 0.07 cal s 0.293 W 1 W 3.41214 BTU h 0.238846 cal s 2.3.7 Power BTU h or horsepower hp are normally used or in SI kilowatts kW . See Table 2.7. 2.3.8 Flow The basic unit of volume flowrate is US gallon min in SI it is litres s . 1 US gallon 4 quarts 128 US fluid ounces 231in3 Fundamental dimensions and units 13 1 US gallon 0.8 British imperial gallons 3.78833 litres 1 US gallon minute 6.31401 X 10-5 m3 s 0.2273 m3 h 1 m3 s 1000 litres s 1 litre s 2.12 ft3 min T71 A m J C 1 I c Fig. 2.4 Temperature T 300 conversions 250 HH20 210 100 C 140 200 90 190 180 80 170 _ F C 2500 1000 2000 900 1500 800 700 1000 600 900 500 780000 400 600 300 500 400 200 160 4470 150 140 60 130 120 50 110 40 100 90 _ 30 80 -it 70 JH20 60 50 -Ị E-10 40 30 0 20 10 10 0 44-20 -10 4 -20i4-30 -30 44 -40 ị r-40 .Ĩ 1 -160 - C -50 44 -180 I--120 -200 2 z- 140 -250 - --160 _onn j j- 180 300 -200 -350 -p -400 -t-250 -60 -Ị -50 -70 4- -80 X vO 4-60 -90 4-70 80 -100 -120 4-90 -140 - .
