Two bars, A and B, each of length 2.0 m and cross sectional area 1.0 mS1U1P12S1S1P0, are placed end to end as shown in the figure. The thermal conductivities of the bars are kS1U1B1AS1U1B0 = 439 J/(s . m . K) and kS1U1B1BS1U1B0 = 887 J/(s . m . K), respectively. The left end of bar A is maintained at 373 K while the right end of B is maintained at 273 K. -What is the temperature at the interface between A and B?

A) 296 K B) 306 K C) 313 K D) 323 K E) 332 K A) 296 K B) 306 K C) 313 K D) 323 K E) 332 K

Two bars, A and B, each of length 2.0 m and cross sectional area 1.0 mS1U1P12S1S1P0, are placed end to end as shown in the figure. The thermal conductivities of the bars are kS1U1B1AS1U1B0 = 439 J/(s . m . K) and kS1U1B1BS1U1B0 = 887 J/(s . m . K), respectively. The left end of bar A is maintained at 373 K while the right end of B is maintained at 273 K. -How much heat passes the interface between A and B in 6.0 s?

A) 6.0 × 104 J B) 1.5 × 103 J C) 1.2 × 105 J D) 8.8 × 104 J E) 3.0 × 104 J A) 6.0 × 104 J B) 1.5 × 103 J C) 1.2 × 105 J D) 8.8 × 104 J E) 3.0 × 104 J

Assume that the sun is a sphere of radius 6.96 × 108 m and that its surface temperature is 5.8 × 103 K. If the sun radiates at a rate of 3.90 × 1026 W and is a perfect emitter, at what rate is energy emitted per square meter at the sun's surface?

A) 5.6 × 107 W/m2 B) 6.4 × 107 W/m2 C) 5.6 × 1017 W/m2 D) 12.8 × 107 W/m2 E) 25.6 × 107 W/m2 A) 5.6 × 107 W/m2 B) 6.4 × 107 W/m2 C) 5.6 × 1017 W/m2 D) 12.8 × 107 W/m2 E) 25.6 × 107 W/m2

On a cold winter day, the outside temperature is -5.0 °C while the interior of a well-insulated garage is maintained at 20.0 °C by an electric heater. Assume the walls have a total area of 75 m2, a thickness of 0.15 m, and a thermal conductivity of 0.042 W/(m · C°). What is the cost to heat the garage for six hours at these temperatures if the cost of electricity is $ 0.11/kWh? Note: 1 kWh = 3.6 × 106 J.

A) $ 0.18 B) $ 0.44 C) $ 0.61 D) $ 0.35 E) $ 1.09 A) $ 0.18 B) $ 0.44 C) $ 0.61 D) $ 0.35 E) $ 1.09

Exam 13: The Transfer of Heat

A blue supergiant star has a radius of 7.4 × 10¹⁰ m. The spherical surface behaves as a blackbody radiator. If the surface temperature is 2.4 × 10⁴ K, what is the rate at which energy is radiated from the star?

(Multiple Choice)

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Question 21

Two kilograms of ice at 0.0 °C are placed in a sealed glass container [k = 0.80 W/(m · C°)]. The container is then placed in a room that is maintained at 30.0 °C. The top cover is a thermal insulator and all other sides of the container are exposed to room air. The surface area of the container is 6.53 × 10^-2 m²; and its glass walls are 0.0050 m thick. -How much heat is required to melt the ice?

(Multiple Choice)

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Question 22

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 6.3 × 10^-⁵ m²? The Stefan-Boltzmann constant is 5.67 × 10^-⁸ W/(m² · K²).

(Multiple Choice)

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Question 23

Two bars, A and B, each of length 2.0 m and cross sectional area 1.0 m², are placed end to end as shown in the figure. The thermal conductivities of the bars are k_A = 439 J/(s . m . K) and k_B = 887 J/(s . m . K), respectively. The left end of bar A is maintained at 373 K while the right end of B is maintained at 273 K. -What is the temperature at the interface between A and B?

(Multiple Choice)

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Question 24

Complete the following statement: Most of the heat that is lost to space from the earth occurs by

(Multiple Choice)

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Question 25

Which one of the following is not an example of convection?

(Multiple Choice)

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Question 26

Two identical solid spheres have the same temperature. One of the spheres is cut into two identical pieces. These two hemispheres are then separated. The intact sphere radiates an energy Q during a given time interval. During the same interval, the two hemispheres radiate a total energy Q'. What is the ratio Q'/Q?

(Multiple Choice)

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Question 27

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

(Multiple Choice)

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Question 28

Two bars, A and B, each of length 2.0 m and cross sectional area 1.0 m², are placed end to end as shown in the figure. The thermal conductivities of the bars are k_A = 439 J/(s . m . K) and k_B = 887 J/(s . m . K), respectively. The left end of bar A is maintained at 373 K while the right end of B is maintained at 273 K. -How much heat passes the interface between A and B in 6.0 s?

(Multiple Choice)

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Question 29

Assume that the sun is a sphere of radius 6.96 × 10⁸m and that its surface temperature is 5.8 × 10³ K. If the sun radiates at a rate of 3.90 × 10²⁶ W and is a perfect emitter, at what rate is energy emitted per square meter at the sun's surface?

(Multiple Choice)

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Question 30

On a cold winter day, the outside temperature is -5.0 °C while the interior of a well-insulated garage is maintained at 20.0 °C by an electric heater. Assume the walls have a total area of 75 m², a thickness of 0.15 m, and a thermal conductivity of 0.042 W/(m · C°). What is the cost to heat the garage for six hours at these temperatures if the cost of electricity is $ 0.11/kWh? Note: 1 kWh = 3.6 × 10⁶ J.

(Multiple Choice)

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Question 31

The sun continuously radiates energy into space in all directions. Some of the sun's energy is intercepted by the earth. The average temperature of the surface of the earth remains a little above 300 K. Why doesn't the earth's temperature rise as it intercepts the sun's energy?

(Multiple Choice)

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Question 32

Which one of the following statements concerning the Stefan-Boltzmann equation is true?

(Multiple Choice)

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Question 33

Heat is conducted by two cylindrical rods, one carbon and one aluminum, with identical cross-sectional 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 aluminum is 240 J/(s . m . C°). What percentage of the total energy transferred by the two rods each second is conducted by the silver rod?

(Multiple Choice)

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Question 34

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?

(Multiple Choice)

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Question 35

Which one of the following statements concerning emissivity is false?

(Multiple Choice)

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Question 36

A slab of insulation is made of three layers, as Drawing I indicates. Each of the layers A, B, and C has the same thickness, but a different thermal conductivity. Heat flows through the slab, and the temperatures are as shown. What are the temperatures T₁ and T₂ in Drawing II where the layers are arranged in a different order?

(Multiple Choice)

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Question 37

Which one of the following objects, all initially at the same temperature, will be most efficient in losing heat?

(Multiple Choice)

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Question 38

A hot metal ball is hung in an oven that is maintained at 700 K; and it cools. When the temperature of the ball is 950 K, it is losing heat at a rate of 0.15 J/min. At what rate will the ball lose heat when the ball reaches 820 K? Assume that the emissivity of the ball and its surface area do not change appreciably with temperature.

(Multiple Choice)

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Question 39

Two cylindrical steel rods A and B have radii of 0.02 m and 0.04 m, respectively. 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, L_A/L_B?

(Multiple Choice)

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Question 40

Showing 21 - 40 of 42

Exam 13: The Transfer of Heat

A blue supergiant star has a radius of 7.4 × 1010 m. The spherical surface behaves as a blackbody radiator. If the surface temperature is 2.4 × 104 K, what is the rate at which energy is radiated from the star?

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 6.3 × 10-5 m2? The Stefan-Boltzmann constant is 5.67 × 10-8 W/(m2 · K2).

Complete the following statement: Most of the heat that is lost to space from the earth occurs by

Which one of the following is not an example of convection?

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

Assume that the sun is a sphere of radius 6.96 × 108 m and that its surface temperature is 5.8 × 103 K. If the sun radiates at a rate of 3.90 × 1026 W and is a perfect emitter, at what rate is energy emitted per square meter at the sun's surface?

The sun continuously radiates energy into space in all directions. Some of the sun's energy is intercepted by the earth. The average temperature of the surface of the earth remains a little above 300 K. Why doesn't the earth's temperature rise as it intercepts the sun's energy?

Which one of the following statements concerning the Stefan-Boltzmann equation is true?

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?

Which one of the following statements concerning emissivity is false?

Which one of the following objects, all initially at the same temperature, will be most efficient in losing heat?

Two cylindrical steel rods A and B have radii of 0.02 m and 0.04 m, respectively. 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?

Introduction and Mathematical Concepts

Kinematics in One Dimension

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Forces and Newtons Laws of Motion

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The Refl Ection of Light: Mirrors

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A blue supergiant star has a radius of 7.4 × 10¹⁰ m. The spherical surface behaves as a blackbody radiator. If the surface temperature is 2.4 × 10⁴ K, what is the rate at which energy is radiated from the star?

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 6.3 × 10^-⁵ m²? The Stefan-Boltzmann constant is 5.67 × 10^-⁸ W/(m² · K²).

Assume that the sun is a sphere of radius 6.96 × 10⁸m and that its surface temperature is 5.8 × 10³ K. If the sun radiates at a rate of 3.90 × 10²⁶ W and is a perfect emitter, at what rate is energy emitted per square meter at the sun's surface?

Two cylindrical steel rods A and B have radii of 0.02 m and 0.04 m, respectively. 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, L_A/L_B?