1. How much heat was needed to raise the bullet to its final temperature?

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1 Name: Date: Use the following to answer question 1: A kg lead bullet of volume m 3 at 20.0 C hits a block that is made of an ideal thermal insulator and comes to rest at its center. At that time, the temperature of the bullet is 327 C. Use the following information for lead: coefficient of linear expansion: = /C specific heat capacity: c = 128 J/(kg C ) latent heat of fusion: Lf = J/kg melting point: Tmelt = 327 C 1. How much heat was needed to raise the bullet to its final temperature? A) 963 J B) 1960 J C) 3640 J D) 3880 J E) 4440 J 2. Complete the following statement: Bimetallic strips used as adjustable switches in electric appliances consist of metallic strips that must have different A) mass. B) length. C) volume. D) expansion coefficients. E) specific heat capacities. Page 1

2 Use the following to answer question 3: Heat is added to a 1.0-kg solid sample of a material at 200 C. The figure shows the temperature of the material as a function of the heat added. 3. Which one of the following statements concerning this substance is true? A) It boils at 300 C. B) It melts at 200 C. C) It is a liquid at 200 C. D) It can coexist as a solid and a liquid at 50 C. E) It can exist as a solid, liquid, and gas at 150 C. 4. Complete the following statement: A temperature decrease of 30 C is equal to a temperature decrease of A) 30 F. B) 30 K. C) 17 F. D) 26 F. E) 303 K. Page 2

3 5. A kg ice cube at 0 C is placed in an insulated box that contains kg of steam at 100 C. What is the equilibrium temperature reached by this closed system? Note: Assume that all of the ice melts. A) 22.7 C B) 33.6 C C) 44.9 C D) 50.7 C E) 66.4 C 6. The coefficient of linear expansion of a certain solid is /C. Assuming this solid behaves like most solids, what is its coefficient of volume expansion? A) /C B) /C C) /C D) /C E) /C 7. Complete the following statement: The term heat most accurately describes A) the internal energy of an object. B) a measure of how hot an object is. C) the absolute temperature of an object. D) the molecular motion inside of an object. E) the flow of energy due to a temperature difference. 8. Which one of the following properties could not be used as a temperature sensitive property in the construction of a thermometer? A) the change in mass of a solid B) the change in volume of a liquid C) the change in length of a metal rod D) the change in electrical resistance of a wire E) the change in pressure of a gas at constant volume Page 3

4 9. 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 Kelvins. 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. 10. An ordinary mercury thermometer at room temperature is quickly placed in a beaker of hot water. The mercury column is observed to drop slightly before it rises to the final equilibrium temperature. Which one of the following statements is the best explanation for this behavior? A) The glass envelope expands before the heat reaches the mercury. B) The expansion coefficient of glass is larger than that of mercury. C) Both the mercury and the glass initially expand, but at different rates. D) Initially, the mercury contracts. E) Initially, the glass envelop contracts. 11. In an insulated container, 0.50 kg of steam, initially at 140 C, is mixed with 2.0 kg of ice, initially at 20.0 C. What is the final temperature inside the container if heat exchanges with the container are ignored? A) 16 C B) 50 C C) 60 C D) 64 C E) 86 C 12. The coefficient of linear expansion of steel is /C. A railroad track is made of individual rails of steel 1.0 km in length. By what length would these rails change between a cold day when the temperature is 10 C and a hot day at 30 C? A) 0.62 cm B) 24 cm C) 48 cm D) 480 cm E) 620 cm Page 4

5 13. Which one of the following statements explains why it is difficult to measure the coefficient of volume expansion for a liquid? A) Liquids are more compact than solids. B) Liquids are more compact than gases. C) Liquids tend to expand more slowly than solids. D) The liquid will lose heat to the containing vessel. E) The volume of the containing vessel will also increase. 14. Which one of the following statements is the best explanation for the fact that metal pipes that carry water often burst during cold winter months? A) Water contracts upon freezing while the metal expands at lower temperatures. B) The metal contracts to a greater extent than the water. C) The interior of the pipe contracts less than the outside of the pipe. D) Water expands upon freezing while the metal contracts at lower temperatures. E) Both the metal and the water expand, but the water expands to a greater extent. 15. Which one of the following statements best explains why convection does not occur in solids? A) Molecules in a solid are more closely spaced than in a gas. B) The molecules in a solid are not free to move throughout the volume of the solid. C) Molecules in a solid vibrate at a lower frequency than those in a liquid. D) Solids are more compressible than liquids. E) Solids are less compressible than gases. 16. Object A has an emissivity of 0.95; and its temperature is 25 C. At what temperature (in degrees Celsius) does object B, whose emissivity is 0.60, emit radiation at the same rate as object A if both objects have the same surface area? A) 28 C B) 40 C C) 61 C D) 73 C E) 97 C 17. How much heat passes the interface between A and B in 5.0 s? A) J B) J C) J D) J E) J Page 5

6 18. If a beaker of water is placed under a broiler so that the heating coil is above the beaker. It is observed that only the surface layer boils. The water at the bottom of the beaker remains close to the initial temperature of the water. Which of the following statements is the most reasonable conclusion to be drawn from these observations? A) Water is a poor conductor of heat. B) The sample must contain impurities. C) Water is easily heated by radiation. D) Water exhibits anomalous thermal behavior. E) The molecular motion in the sample is not random. 19. Which of the following materials is the best thermal conductor? A) diamond B) Styrofoam C) nitrogen gas D) concrete E) goose down 20. Which one of the following graphs shows the rate at which heat is emitted from a hot body as a function of its Kelvin temperature T? A) (a) B) (b) C) (c) D) (d) E) (e) 21. In an experiment to determine the thermal conductivity of a bar of a new alloy, one end of the bar is maintained at 0.0 C and the other end at C. The bar has a cross-sectional area of 1.0 cm 2 and a length of 15 cm. If the rate of heat conduction through the bar is 24 W, what is the thermal conductivity of the bar? A) 24 W/(m C ) B) 360 W/(m C ) C) 160 W/(m C ) D) 63 W/(m C ) E) W/(m C ) Page 6

7 22. Complete the following statement: The interior of a thermos bottle is silvered to minimize heat transfer due to A) radiation. B) conduction. C) conduction and convection. D) conduction and radiation. E) conduction, convection, and radiation. 23. Assume that the sun is a sphere of radius m and that its surface temperature is K. If the sun radiates at a rate of W and is a perfect emitter, at what rate is energy emitted per square meter at the sun's surface? A) W/m 2 B) W/m 2 C) W/m 2 D) W/m 2 E) W/m A blue supergiant star has a radius of m. The spherical surface behaves as a blackbody radiator. If the surface temperature is K, what is the rate at which energy is radiated from the star? A) J/s B) J/s C) J/s D) J/s E) J/s 25. 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 (are) primarily responsible for boiling the sample? A) conduction B) convection C) radiation D) both conduction and radiation E) both conduction and convection Page 7

8 26. Assuming a filament in a 100 W light bulb acts like a perfect blackbody, what is the temperature of the hottest portion of the filament if it has a surface area of m 2? The Stefan-Boltzmann constant is W/(m 2 K 2 ). A) 130 K B) 1100 K C) 2300 K D) 5800 K E) K 27. A granite wall has a thickness of 0.61 m and a thermal conductivity of 2.1 W/(m C ). The temperature on one face of the wall is 3.2 C and 20.0 C on the opposite face. How much heat is transferred in one hour through each square meter of the granite wall? A) J/m 2 B) J/m 2 C) J/m 2 D) J/m 2 E) 58 J/m Which object will emit more electromagnetic radiation than it absorbs from its surroundings? A) a 600 C lead sphere in a 700 C oven B) a girl scout sitting close to a campfire C) an ice cube in beaker of water at 50 C D) a 200 C copper coin in a beaker of water at 98 C E) an ice cube in thermal equilibrium with the interior of a freezer 29. The two ends of an iron rod are maintained at different temperatures. The amount of heat that flows through the rod by conduction during a given time interval does not depend upon A) the length of the iron rod. B) the thermal conductivity of iron. C) the temperature difference between the ends of the rod. D) the mass of the iron rod. E) the duration of the time interval. 30. Which one of the following statements concerning the Stefan-Boltzmann equation is true? A) This equation applies only to perfect radiators. B) This equation applies only to perfect absorbers. C) This equation is valid with any temperature units. D) This equation describes the transport of thermal energy by conduction. E) The equation can be used to calculate the power absorbed by any surface. Page 8

9 31. Complete the following statement: Most of the heat that is lost to space from the earth occurs by A) conduction. B) convection. C) radiation. D) both conduction and radiation. E) both conduction and convection. 32. Complete the following statement: The transfer of heat by convection will occur A) only in metals. B) only in a vacuum. C) only in non-metallic solids. D) with or without the presence of matter. E) only in the presence of a liquid or a gas. 33. Suppose you are sitting next to a fireplace in which there is a fire burning. One end of a metal poker has been left in the fire. Which one of the following statements concerning this situation is true? A) You can feel the heat of the fire primarily because of convection. B) The end of the poker that is not in the fire is warmed through conduction. C) Heat escapes through the chimney primarily through conduction. D) You can feel the heat of the fire primarily because of conduction. E) The end of the poker that is not in the fire is warmed through convection. 34. Heat is conducted by two cylindrical rods, one carbon and one silver, with identical crosssectional area and length. The temperature difference between the ends of each rod is the same. Carbon has a thermal conductivity of 1100 J/(s m C ) and that of silver is 420 J/(s m C ). What percentage of the total energy transferred by the two rods each second is conducted by the silver rod? A) 64 % B) 28 % C) 50 % D) 36 % E) 72 % Page 9

10 35. The power radiated by a distant star is W. The radius of the star, which may be considered a perfect radiator, is m. Determine the surface temperature of the star. A) 2690 K B) 4430 K C) 7240 K D) 8510 K E) 9770 K 36. Which one of the following statements concerning emissivity is false? A) The emissivity is 1.0 for a perfect radiator. B) The emissivity is 1.0 for a perfect absorber. C) Emissivity depends on the condition of the surface. D) Emissivity is a dimensionless quantity. E) Emissivity depends on the surface area of the object. 37. Which one of the following objects, all initially at the same temperature, will be most efficient in losing heat? A) a dull black box in vacuum B) a dull black box in air C) a box with an emissivity of 0.1 D) a polished silver box in air E) a polished silver box in vacuum Page 10

11 Answer Key 1. B 2. D 3. D 4. B 5. B 6. C 7. E 8. A 9. C 10. A 11. C 12. C 13. E 14. D 15. B 16. C 17. A 18. A 19. A 20. D 21. B 22. A 23. B 24. D 25. E 26. C 27. A 28. D 29. D 30. E 31. C 32. E 33. B 34. B 35. A 36. E 37. B Page 11