Question 1

Complete the following statement: The space between the inner walls of a thermos bottle is evacuated to minimize heat transfer by

Accepted Answer

A) radiation. 
B) conduction. 
C) conduction and convection. 
D) conduction and radiation. 
E) conduction,convection,and radiation. 
A) radiation. 
B) conduction. 
C) conduction and convection. 
D) conduction and radiation. 
E) conduction,convection,and radiation.

Question 2

A person steps out of the shower and dries off.The person's skin with an emissivity of 0.70 has a total area of 1.2 m² and a temperature of 33 °C.What is the net rate at which energy is lost to the room through radiation by the naked person if the room temperature is 24 °C?

Accepted Answer

A) 0.041 W 
B) 25 W 
C) 81 W 
D) 67 W 
E) 47 W 
A) 0.041 W 
B) 25 W 
C) 81 W 
D) 67 W 
E) 47 W

Question 3

Complete the following statement: The transfer of heat by convection will occur

Accepted Answer

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. 
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.

Question 4

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?

Accepted Answer

A) (
A)  
B) (
B)  
C) (
C)  
D) (
D)  
E) (
E)  
A) (
A)  
B) (
B)  
C) (
C)  
D) (
D)  
E) (
E)

Question 5

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
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?

Accepted Answer

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

Question 6

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.

Accepted Answer

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

Question 7

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   during a given time interval.During the same interval,the two hemispheres radiate a total energy  .What is the ratio

Accepted Answer

A) 2.0 
B) 0.50 
C) 4.0 
D) 1.5 
E) 0.25 
A) 2.0 
B) 0.50 
C) 4.0 
D) 1.5 
E) 0.25

Question 8

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 is240 J/(s×m ×C°).What percentage of the total energy transferred by the two rods each second is conducted by the silver rod?

Accepted Answer

A) 64 % 
B) 18 % 
C) 30 % 
D) 46 % 
E) 82 % 
A) 64 % 
B) 18 % 
C) 30 % 
D) 46 % 
E) 82 %

Question 9

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
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 rate of heat transfer through this combination?

Accepted Answer

A) 3.7 × 10³ J/s 
B) 6.4 × 10³ J/s 
C) 8.8 × 10³ J/s 
D) 1.5 × 10⁴ J/s 
E) 2.2 × 10⁴ J/s 
A) 3.7 × 10³ J/s 
B) 6.4 × 10³ J/s 
C) 8.8 × 10³ J/s 
D) 1.5 × 10⁴ J/s 
E) 2.2 × 10⁴ J/s

Question 10

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?

Accepted Answer

A) T₁ = 230 °C and T₂ = 170 °C 
B) T₁ = 200 °C and T₂ = 180 °C 
C) T₁ = 220 °C and T₂ = 160 °C 
D) T₁ = 180 °C and T₂ = 160 °C 
E) T₁ = 210 °C and T₂ = 190 °C 
A) T₁ = 230 °C and T₂ = 170 °C 
B) T₁ = 200 °C and T₂ = 180 °C 
C) T₁ = 220 °C and T₂ = 160 °C 
D) T₁ = 180 °C and T₂ = 160 °C 
E) T₁ = 210 °C and T₂ = 190 °C

Question 11

Suppose you are sitting next to a fire burning in a fireplace.One end of a metal poker has been left in the fire.Which one of the following statements concerning this situation is true?

Accepted Answer

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. 
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.

Question 12

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?

Accepted Answer

A) 1.2 × 10³ J/s 
B) 9.4 × 10¹⁹ J/s 
C) 2.0 × 10²³ J/s 
D) 8.2 × 10³² J/s 
E) 1.3 × 10³³ J/s 
A) 1.2 × 10³ J/s 
B) 9.4 × 10¹⁹ J/s 
C) 2.0 × 10²³ J/s 
D) 8.2 × 10³² J/s 
E) 1.3 × 10³³ J/s

Question 13

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?

Accepted Answer

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

Question 14

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
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?

Accepted Answer

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

Question 15

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

Accepted Answer

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. 
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.

Question 16

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.

Accepted Answer

A) 0.1 J/min 
B) 0.007 J/min 
C) 0.08 J/min 
D) 0.06 J/min 
E) 0.04 J/min 
A) 0.1 J/min 
B) 0.007 J/min 
C) 0.08 J/min 
D) 0.06 J/min 
E) 0.04 J/min

Question 17

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

Accepted Answer

A) Smoke rises above a fire. 
B) An eagle soars on an updraft of wind. 
C) A person gets a suntan on a beach. 
D) Spaghetti is cooked in water. 
E) An electric heater warms a room. 
A) Smoke rises above a fire. 
B) An eagle soars on an updraft of wind. 
C) A person gets a suntan on a beach. 
D) Spaghetti is cooked in water. 
E) An electric heater warms a room.

Question 18

Which one of the following processes does not occur during the convective transfer of heat within a container of air?

Accepted Answer

A) The volume of a warmed part of the air is reduced and its density increases. 
B) A continuous flow of warmer and cooler parts of air is established. 
C) The flow of air molecules results in a flow of heat. 
D) The cooler portion of the air surrounding a warmer part exerts a buoyant force on it. 
E) As the warmer part of the air moves,it is replaced by cooler air that is subsequently warmed. 
A) The volume of a warmed part of the air is reduced and its density increases. 
B) A continuous flow of warmer and cooler parts of air is established. 
C) The flow of air molecules results in a flow of heat. 
D) The cooler portion of the air surrounding a warmer part exerts a buoyant force on it. 
E) As the warmer part of the air moves,it is replaced by cooler air that is subsequently warmed.

Question 19

Which of the following materials is the best thermal conductor?

Accepted Answer

A) diamond 
B) Styrofoam 
C) nitrogen gas 
D) concrete 
E) goose down 
A) diamond 
B) Styrofoam 
C) nitrogen gas 
D) concrete 
E) goose down

Question 20

Which object will emit more electromagnetic radiation than it absorbs from its surroundings?

Accepted Answer

A) a 600 °C copper 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 
A) a 600 °C copper 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

Complete the following statement: The space between the inner walls of a thermos bottle is evacuated to minimize heat transfer by

A person steps out of the shower and dries off.The person's skin with an emissivity of 0.70 has a total area of 1.2 m² and a temperature of 33 °C.What is the net rate at which energy is lost to the room through radiation by the naked person if the room temperature is 24 °C?

Complete the following statement: The transfer of heat by convection will occur

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?

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 during a given time interval.During the same interval,the two hemispheres radiate a total energy .What is the ratio

Suppose you are sitting next to a fire burning in a fireplace.One end of a metal poker has been left in the fire.Which one of the following statements concerning this situation is true?

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?

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?

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

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

Which one of the following processes does not occur during the convective transfer of heat within a container of air?

Which of the following materials is the best thermal conductor?

Which object will emit more electromagnetic radiation than it absorbs from its surroundings?

Fluids

The Ideal Gas Law and Kinetic Theory

Thermodynamics

The Principle of Linear Superposition and Interference Phenomena

Electric Circuits

Electromagnetic Induction

The Refl Ection of Light: Mirrors

The Refraction of Light: Lenses and Optical Instruments

Particles and Waves

Filters

Exam 13: The Transfer of Heat

Complete the following statement: The space between the inner walls of a thermos bottle is evacuated to minimize heat transfer by

A person steps out of the shower and dries off.The person's skin with an emissivity of 0.70 has a total area of 1.2 m² and a temperature of 33 °C.What is the net rate at which energy is lost to the room through radiation by the naked person if the room temperature is 24 °C?

Complete the following statement: The transfer of heat by convection will occur

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?

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 during a given time interval.During the same interval,the two hemispheres radiate a total energy .What is the ratio

Suppose you are sitting next to a fire burning in a fireplace.One end of a metal poker has been left in the fire.Which one of the following statements concerning this situation is true?

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?

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?

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

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

Which one of the following processes does not occur during the convective transfer of heat within a container of air?

Which of the following materials is the best thermal conductor?

Which object will emit more electromagnetic radiation than it absorbs from its surroundings?

Fluids

The Ideal Gas Law and Kinetic Theory

Thermodynamics

The Principle of Linear Superposition and Interference Phenomena

Electric Circuits

Electromagnetic Induction

The Refl Ection of Light: Mirrors

The Refraction of Light: Lenses and Optical Instruments

Particles and Waves

Filters