Please Show All work.. QUESTION 1 Auubeman mecanicates aretingof assersityof0ce1

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Please Show All work..

QUESTION 1 Auubeman mecanicates aretingof assersityof0ce1m The air is at 25 deg C and 60 psig. If air at 0 deg C and 1 atm has a density of 0.081 lb/fth3, what is the pressure drop in atmospheres? QUESTION 2 If the pressure drop in the previous problem is 51 psf, corresponding to a manometer reading of 10 inches of water, what percentage of error is introduced if the density of the air in the manometer leads is neglected? NOTE: You should need the density of water here, but should not use the density of air from the previous question (or the specific T or P values of air).

Explanation / Answer

Question 1

In order to solve this first we need to obtain he density of air at 25 oC and 60 psig

In order to do this we will make use of ideal gas law

(P1/rhou1*T1) = (P2/(Rhou2*T2)

From this we will find density at initial condition

T1 = 25 oC = 298.15 K

T2 = 0 oC = 273.15

P1 =60 psig = 74.69 psia = 50.08 atm

P2 = 1 atm

Hence density at T1 will be

Rhou1 = (50.08/298.15)*(273.15/1)*0.081 = 3.7163 lb/ft3

Density of water = 62.428 lb/ft3

Pressure head = (1- Rhou_air/Rhou_water)*H = (1-3.7163/62.428)*10 = 9.4047 inches = 0.238 m =0.78 ft

P =Rhou*g*h = 3.7163*32.2*0.78 =93.3388 lbf//ft2

Question 2

P = 51 psf = 51 lbf/ft2

% error = (93.338-51)/93.338 *100 = 45.36%

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