ACLC COLLEGE
Pre fi Examination
Thermodynamics
Prepared by: Arwin Jo N. Dominguez
GENERAL RULE: ANYONE CAUGHT CHEATING WILL BE GIVEN A GRADE OF “5.0” IN THIS SUBJECT AS
PREVIOUSLY DISCUSSED DURING ORRIENTATION. ILLEGIBLE ANSWERS WILL BE CONSIDERED
INCORRECT.
I.
Problem Solving: ( 25 points each )
1. A drum 6 in. in diameter and 40 in. long contained acetylene at 250 psia and 90(deg)F.After
some of the acetylene was used, the pressure was 200 psia and the temperature was 85degF,
(a) What proportion of the acetylene was used? (b) what volume would the used acetylene
occupy at 14.7 psia and 80(deg)F? R for acetylene is 59.35 ft.lb/lb(deg)R.
2. The volume of a 6 x 12-ft tank is 339.3 cu ft. it contains air at 200 psig and 85(deg)F. how many
1-cu ft drums can be filled to 50 psig and 80(deg)F if it is assumed that the air temperature in
the tank remains at 85(deg)F? The drums have been sitting around in the atmosphere which is
at 14 7 psia and 80(deg)F. ( R to be given )
3. It is planned to lift and move logs from almost inaccessible forest areas by means of balloons.
Helium at atmospheric pressure (101.325 kPa) and temperature 21.1(deg)C is to be used in
the balloons. What minimum balloon diameter (assume spherical shape) will be required for a
gross lifting force of 20 metric tons?
4. Two vessels A and B of different sizes are connected by a pipe with a valve. Vessel A contains
142 L of air at 2,767.92 kPa, 93.33(deg)C. Vessel B, of unknown volume, contains air at 68.95
kPa, 4.44(deg)C. The valve is opened and, when the properties have been determined, it is
found that p = 1378.96 kPa, t = 43.33(deg)C. what is the volume of vessel B?
Some people give hapiness wherever they go, some whenever
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