Biology Forums - Study Force

Gas in a container increases its pressure from 1 atm to 3 atm while keeping its volume constant. Find the work done (in J) by the gas if the volume is 5 liters.
 a. 0
  b. 3
  c. 5
  d. 15
  e. 15  102

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[Ques. 2] Gas in a container expands at a constant pressure of 3 atm. Find the work done (in J) by the gas if the initial volume is 5 liters and the final volume is 10 liters.
 a. 0
  b. 150
  c. 15
  d. 1 500
  e. 1.5

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[Ques. 3] The work done in the expansion from an initial to a final state
 a. is the area under the curve of a PV diagram.
  b. depends only on the end point.
  c. is independent of the path.
  d. is the slope of a PV curve.
  e. equals P(VF  Vi).

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[Ques. 4] A 5-g coin is dropped from a 300-m building. If it reaches a terminal velocity of 45 m/s, and the rest of the energy is converted to heating the coin, what is the change in temperature (in C) of the coin? (The specific heat of copper is 387 J/kg/C.)
 a. 9
  b. 2
  c. 5
  d. 21
  e. 0.5

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[Ques. 5] A 100-kg student eats a 200-Calorie doughnut. To burn it off, he decides to climb the steps of a tall building. How high (in m) would he have to climb to expend an equivalent amount of work? (1 food Calorie = 103 calories.)
 a. 273
  b. 623
  c. 418
  d. 854
  e. 8 400

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[Ques. 6] A super-insulated house is at a temperature of 20C. The temperature outside is 0C. The surface area of the house is 200 m2, and the emissivity is 1 . Approximately how much energy is radiated (in W) per second?
 a. 20 000
  b. 2 000
  c. 200
  d. 2
  e. 0.2

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[Ques. 7] A child has a temperature of 101F. If her total cross-sectional area is 2 m2, find the energy lost each second (in W) due to radiation, assuming the emissivity is 1 . (Assume the room temperature is 70F.)
 a. 217
  b. 180
  c. 90
  d. 68
  e. 850

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[Ques. 8] A cup of coffee is enclosed on all sides in an insulated container 1/2 cm thick in the shape of a cube 10 cm on a side. The temperature of the coffee is 95C, and the temperature of the surroundings is 21C. Find the rate of heat loss (in J/s) due to conduction if the thermal conductivity of the cup is 2  104 cal/s/cm/C.
 a. 62
  b. 74
  c. 230
  d. 160
  e. 12

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[Ques. 9] A wall is constructed of a 2 inch layer of fiberglass board (R = 8) and six inches of fiberglass batting (R = 19). If the temperature on the outside surface of the fiberglass board is 50F and the temperature on the inside surface of the fiberglass batting is 68F, what is the temperature (in F) at the interface? (The units of R are ft2/F/h/BTU.)
 a. 62
  b. 58
  c. 55
  d. 65
  e. 52

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[Ques. 10] A slab of concrete and an insulating board are in thermal contact with each other. The temperatures of their outer surfaces are 68F and 50F. Determine the rate of heat transfer (in BTU/ft2/h) if the R values are 1.93 and 8.7 ft2/F/h/BTU, respectively.
 a. 9.7
  b. 2.5
  c. 5.3
  d. 1.7
  e. 28

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