PHYSICS DEPARTMENT
PHY2004                         Exam #3              November 20, 1996
Stanton
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NAME
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density of water = 1000 kg / m3= 1 g/cm3= 62.4 lb/ft3

1 atm = Atmospheric Pressure = 14.7 lb/in2 = 101 kPa Heat of Vaporization of Water = 539 cal/g

Heat of Fusion of Water = 80 cal/g

k B (Boltzmann's constant) = 1.38 x 10-23 J/K

NA= 6.02 X 1026 /kmol = 6.02 x 1023 /mol

g = 9.8 m/s2= 32.2 ft/s2

R = 8314 (J/kmol K)

Cwater = 1 cal/(g-oC)

Csteam = 0.46 cal/(g-oC)

Cice = 0.5 cal/(g-oC)

1 cal = 4.184 J

1 GPa = 1.0 x 109 Pa

1 kcal = 1000 cal = 1 nutritionist's Calorie

  1. A submarine is under water at a depth of 1600 m (approximately 1 mile). What is the pressure on the hull of the submarine? Give the answer in units of atm, atmospheric pressure (1 atm = 1.01 x 105 Pa). Assume that ocean water has the same density as regular water.

    1. 156
    2. 15.8
    3. 35,000
    4. 1.6 x 105
    5. 78


  2. A certain fluid compresses by 0.5 PERCENT under a pressure of 7 MPa (1 MPa = 106 Pa). What is the BULK MODULUS for this fluid in GPa (1 GPa = 109 Pa)?

    1. 1.4
    2. 0.014
    3. -0.014
    4. 14
    5. 3.5


  3. An iron girder has a cross sectional area of 100 cm2. How large a compressive force (in newtons) is required to shorten the girder by 0.03 PERCENT? Use the table 1 given on the figure sheet.

    1. 2.7 x 105
    2. 3.0 x 107
    3. 2.7 x 10-4
    4. 2.1 x 109
    5. 3.0 x 105


  4. An object weighs 12.5 N in air and has a volume of 350 cm3. How much will it APPEAR to weigh (in N) when completely submerged in water?

    1. 9.1
    2. 12.2
    3. 12.9
    4. 5.6
    5. 9.9


  5. The PRESSURE GAUGE on a 3000-cm3 tank of nitrogen reads 750 kPa. How much volume (in cm3) will the nitrogen occupy at the pressure of the outside air, 100 kPa? Assume temperature is constant.

    1. 2.55 x 104
    2. 2.25 x 104
    3. 2250
    4. 400
    5. 3.53 x 104


  6. Ten kilograms of helium gas (M = 4 kg/kmol) are contained in a 1.0m3 tank at 30oC. What is the ABSOLUTE pressure in the tank? Give your answer in Pa.
    1. 6.3 x 106
    2. 1.0 x 106
    3. 6.2 x 105
    4. 1.0 x 107
    5. 1.0 x 104


  7. * On a winter day in Anchorage, Alaska, the temperature is -20oC. What is the average velocity (in m/s) of a nitrogen molecule (28 kg/kmol)?

    1. 475
    2. 510
    3. 133
    4. 274
    5. 336


  8. How many atoms are there in 12 kg of helium? (MHe = 4kg/kmol).

    1. 1.8 x 1027
    2. 1.8 x 1024
    3. 2.0 x 1026
    4. 2.0 x 1024
    5. 2.4 x 1027


  9. The coefficient of linear expansion for steel is 12 x 10-6 /oC. By what PERCENTAGE would a steel bridge contract from the hotest day of the year (37oC) to the coldest day of the year (-20oC)?

    1. 0.068
    2. 6.8 x 10-4
    3. 0.020
    4. 0.044
    5. 0.37


  10. * How many grams of steam at 180oC are needed to raise the temperature of 500 grams of water from 20oC to 85oC? Csteam = 0.46 cal/(g-oC).

    1. 55
    2. 60
    3. 740
    4. 40
    5. 247


  11. Mount Everest is about 8850 m tall. Ideally, how many kcal (i.e. nutritionist's Calories) would a 75 kg man burn off if he climbed straight to the top? (Assume the body is 100% efficient and neglect any work not associated with the change in height. In reality, one would need many more calories.)

    1. 1550
    2. 1.6 x 106
    3. 6500
    4. 1.6 x 105
    5. 2.7 x 104


  12. * 300 g of water at a temperature of 95oC is mixed with 500 g of water at 20oC. What is the final temperature of the water after mixing?

    1. 48
    2. 67
    3. 92
    4. 58
    5. 53


  13. How much heat (in cal) is needed to change 40 g of ice at -20oC into water at 30oC? Note that Cice = 0.5 cal/(g-oC).

    1. 4800
    2. 1600
    3. 5200
    4. 3200
    5. 4400


  14. An ideal gas is confined to a cylinder by a 10 kg piston as shown in figure 1. When 56 J of heat is added to the gas, the piston raises by 50 cm. What is the change in internal energy of the gas in Joules?

    1. 7
    2. 49
    3. 56
    4. 51
    5. 0


  15. A 50-g block of substance with a specific heat capacity of 2.3 cal/g-oC is heated up 40oC. Assuming the volume change to be negligible, how much did the internal energy U increase? Give your answer in JOULES.

    1. 1.92 x 104
    2. 4600
    3. 46
    4. 1099
    5. 19.2


  16. *What must be the temperature of the Hot Reservoir (IN CELSIUS) for an IDEAL CARNOT engine that exhausts to a Cold Reservoir at a temperature 20oC (i.e. room temperature) if the engine is 50% efficient?

    1. 313
    2. 586
    3. 40
    4. 313
    5. 10


  17. A certain heat engine has an efficiency of 30%. For each 1000 J of heat energy that it takes in, how much heat (in J) does it exhaust?

    1. 700
    2. 300
    3. 3000
    4. 333
    5. 1000


  18. A 10 ft2 sheet of material allows 250 BTU to flow through it in 30 min when the temperature difference across the sheet is 50oF. What is the R-value for the sheet?

    1. 1
    2. 60
    3. 4
    4. 15
    5. 20


  19. An aluminum frying pan is 12.5 cm in radius and is 1 mm thick. It is placed on a hot burner that has a temperature of 130oC. Meat on the inside of the skillet is at temperature of 70oC. How much heat, in cal, is conducted through the bottom of the frying pan in 1 minute? The thermal conductivity of aluminum is k = 0.5 cal/(cm-s-oC).

    1. 8.8 x 106
    2. 2.8 x 106
    3. 1.8 x 105
    4. 8.8 x 105
    5. 2.8 x 105


  20. Refer to table 2. What thickness (in inches) of cork would give the same insulation as 6 inches of brick?

    1. 0.36
    2. 100
    3. 0.97
    4. 0.30
    5. 0.42