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Unformatted text preview: v rms = √ 3 RT = 459ms1 , see Table 2.4 1 d) What is the speed of sound in this parcel? v sound = √ γRT = 0 . 683 v rms = 314ms1 ( γ = c p c v = 7 5 ) 3. A parcel of dry air is expanded adiabatically from 2.3m 3 to 5.4m 3 . Its initial pressure is p = 500hPa, and initial temperature T = 245K. a) What is the mass M of the parcel? M = pV RT = 50000 × 2 . 3 287 × 245 =1.64kg b) What is the ﬁnal pressure? p = p ( V V ) γ = 50000 ( 2 . 3 5 . 4 ) 1 . 400 = 151 . 4hPa c) What is the ﬁnal Temperature? T = T ± p p ² κ = 245 × ( 151 500 ) . 286 =174.0K d) What is the change in enthalpy? Δ H = M c p Δ T = 1 . 64 × 1005 × (174245) =117kJ 2...
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 Spring '07
 NORTH
 Thermodynamics, Energy, 117 kJ, 0.89 k, 135 nm, 314 m

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