Explore BrainMass

Set of 11 questions: Heat and thermodynamics

Please see the attachment.

1. An engine is used to lift a 2700 kg truck to a height of 3.0 m at constant speed. In the lifting process, the engine received 3.3 x 10^5 J of heat from the fuel burned in its interior. What is the efficiency of the engine?

(a) 0.19
(b) 0.24
(c) 0.29
(d) 0.34
(e) 0.39

2. A gasoline engine with an efficiency of 0.40 generates 1500 W of power. If a liter of gasolina has an energy content of 3.7 x 10^7 J, how many liters of gasoline does the engine consume each hour?

(a) 0.36
(b) 0.48
(c) 1.4
(d) 2.8
(e) 6.9

3. A soft drink manufacturer claims that a new diet drink is "low Joule." The label indicates the available energy is 6300 J. What is the equivalent of this energy in Calories (1 Calorie = 1000 cal)?

(a) 0.015 Cal
(b) 0.48 Cal
(c) 1.0 Cal
(d) 1.5 Cal
(e) 4.8 Cal

4. The digital sign outside a local bank reports that the temperature is 44 degrees C. What is the temperature in degrees Fahrenheit?

(a) 56 degrees F
(b) 79 degrees F
(c) 99 degrees F
(d) 111 degrees F
(e) 120 degrees F

5. During an evening news broadcast in Helsinki, Finland, the meteorologist indicated that the day's lowest temperature was -4.0 degrees Celsius. What is the corresponding value of this temperature on the Fahrenheit scale?

(a) -7.2 degrees F
(b) -4.0 degrees F
(c) 17 degrees F
(d) 25 degrees F
(e) 39 degrees F

6. Calculate the rms speed of the oxygen molecules in the air if the temperature is 5.00 degrees C. Note: The mass of the oxygen molecule is 31.9988 u.

(a) 62.0 m/s
(b) 86.3 m/s
(c) 328 m/s
(d) 465 m/s
(e) 487 m/s

7. What is the internal energy of 1.75 kg of helium (atomic mass = 4.00260 u) with a temperature of 100 degrees C?

(a) 4.65 x 10^3 J
(b) 5.44 x 10^5 J
(c) 2.03 x 10^6 J
(d) 8.16 x 10^6 J
(e) 1.22 x 10^7 J

8. Brad spends four hours watching football on television and does 1090 J of work. In the process, his internal energy decreases by 2990 J. Determine the value of Q, including the algebraic sign.

(a) -1900 J
(b) +1900 J
(c) -2990 J
(d) +4080 J
(e) -4080 J

9. When the gas enclosed beneath the piston shown in the figure receives 1930 J of heat, Q, from its surroundings, it performs 2250 J of work in raising the piston. What is the change in the internal energy of the gas?

(a) -320 J
(b) +320 J
(c) -4180 J
(d) +4180 J
(e) zero joules

10. If the coefficient of performance for a refrigerator is 5.0 and 65 J of work are done on the system, how much heat is rejected to the room?

(a) 390 J
(b) 330 J
(c) 260 J
(d) 210 J
(e) 130 J

11. A heat pump is found to remove 2400 J of heat from the exterior of a house and deliver 3500 J of heat to the interior of the house. What is the coefficient of performance of the heat pump?

(a) 1.5
(b) 3.2
(c) 0.31
(d) 3.9
(e) 0.69


Solution Summary

A set of 11 good questions to learn a lot about thermal properties are presented in this solution.