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29:011 COLLEGE PHYSICS I SUMMER 2013 PRACTICE EXAM 4 1. Three thermometers are placed in a closed insulated box and are allowed to reach thermal equilibrium. One is calibrated in Fahrenheit degrees, one in Celsius degrees, and one in Kelvin. The Celsius thermometer reads 40 °C and the Kelvin thermometer reads 233 K. Which one of the following statements is necessarily true? (A) The Kelvin thermometer should read 233 K. (B) The Kelvin thermometer should read 313 K. (C) The Fahrenheit thermometer must read 40 °F. (D) If water were found within the box, it must be in the liquid state. (E) If the temperature of the contents is increased by 10 C°, the reading on the Kelvin thermometer should increase by 273 K. 2. A metal rod 40.0000-cm long at 40 °C is heated to 60 °C. The length of the rod is then measured to be 40.0105 cm. What is the coefficient of linear expansion of the metal? (A) 13 106/C° (B) 22 106/C° (C) 44 106/C° (D) 53 106/C° (E) 71 106/C° 3. How much heat is required to convert 1 kg of water at 10 °C to steam at 100 °C? (A) 2.3106 J (B) 3.8J (C) 2.6105 J (D) 7.1105 J (E) 2.6106 J 4. Two cylindrical steel rods A and B have radii of 0.02 m and 0.04 m, respectively. It is found that the two steel rods conduct the same amount of heat per unit time for the same temperature differences between their two ends. What is the ratio of the lengths of the rods, LA/LB? (A) 0.25 (B) 0.50 (C) 1.00 (D) 2.00 (E) 4.00 5. The power radiated by a distant star is 4.2 1027 W. The radius of the star, which may be considered a perfect radiator, is 1.06 1010 m. Determine the surface temperature of the star. (A) 2690 K (B) 4430 K (C) 7240 K (D) 8510 K (E) 9770 K 6. A beaker of water is placed on a Bunsen burner. As the lower layers of water are heated, they become less dense and rise. This permits cooler layers to move downward and be heated. Eventually, the water boils. Which method(s) of heat transfer is (ar(E) primarily responsible for boiling the sample? (A) conduction (B) convection (C) radiation (D) both conduction and radiation (E) both conduction and convection 7. An ideal gas is contained in a vessel with a moveable piston. Initially, the gas has a volume of 0.018 m3, an absolute pressure of 1.5 atm, and a temperature of 30 °C. The pressure is 0.75 atm when the volume of the container is decreased to 0.009 m3. What is the final temperature of the gas? (A) 76 K (B) 98 K (C) 170 K (D) 240 K (E) 300 K

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8. A mixture of two ideal gases A and B is in thermal equilibrium at 600 K. A molecule of A has one-fourth the mass of a molecule of B and the rms speed of molecules of A is 400 m/s. Determine the rms speed of molecules of B. (A) 100 m/s (B) 200 m/s (C) 400 m/s (D) 800 m/s (E) 1600 m/s 9. 4.8 moles of an ideal monatomic gas is enclosed in a container with a movable piston.

The gas expands and performs work on the piston as 2300 J of heat are added to it. During the process, the temperature of the gas decreases by 45 K. How much work does the gas perform?

(A) 5000 J (B) 3200 J (C) 1400 J (D) 600 J (E) 400 J 10. A heat engine operates in a Carnot cycle between heat reservoirs of temperatures 1000 K and 400 K. The engine discharges 20 J of heat per cycle to the cold reservoir. What is the work output per cycle? (A) 10 J (B) 20 J (C) 30 J (D) 40 J (E) 50 J 11. The displacement of a string due to a transverse wave versus position along the string is shown in the figure. The wave moves with a speed of 30 cm/s. What is the frequency of this wave? (A) 2 Hz (B) 6 Hz (C) 5 Hz (D) 3 Hz (E) 30 Hz 12. How far must one stand from a 0.005 W point sound source if the intensity is at the hearing threshold? Assume the sound waves travel without being disturbed to the listener. (A) 500 m (B) 1 km (C) 2 km (D) 4 km (E) 20 km ---------------------------------------------------------------------------------------------------------------------

1 2 3 4 5 6 7 8 9 10 11 12Answer Key C A E A A E A B A C B E

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