Question 1

A cube at 100.0°C radiates heat at a rate of 80.0 J/s.If the length of each side is cut in half,the rate at which it will now radiate is closest to

Accepted Answer

A)  56.6 J/s. 
B)  40.0 J/s. 
C)  28.3 J/s. 
D)  20.0 J/s. 
E)  10.0 J/s. 
A)  56.6 J/s. 
B)  40.0 J/s. 
C)  28.3 J/s. 
D)  20.0 J/s. 
E)  10.0 J/s.

Question 2

A blacksmith is flattening a steel plate that measures   .He has heated the plate to 900 K.If the emissivity of the plate is 0.75,what is the total rate at which it radiates energy? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 • K4.Ignore any heat it receives from the surroundings.

Accepted Answer

A)  360 W 
B)  760 W 
C)  790 W 
D)  850 W 
E)  880 W 
A)  360 W 
B)  760 W 
C)  790 W 
D)  850 W 
E)  880 W

Question 3

If 2.0 g of water at 0.00°C is to be vaporized,how much heat must be added to it? The specific heat of water is 1.0 cal/g • K,its heat of fusion is 80 cal/g,and its heat of vaporization is   .

Accepted Answer

A)  1100 cal 
B)  1100 kcal 
C)  1200 cal 
D)  1300 cal 
E)  1500 cal 
A)  1100 cal 
B)  1100 kcal 
C)  1200 cal 
D)  1300 cal 
E)  1500 cal

Question 4

What is the net power that a person loses through radiation if her surface area is 1.20 m2,if her emissivity is 0.895,if her skin temperature is 300 K,and if she is in a room that is at a temperature of 17°C? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 • K4.

Accepted Answer

A)  60.3 W 
B)  62.6 W 
C)  65.7 W 
D)  68.4 W 
E)  64.8 W 
A)  60.3 W 
B)  62.6 W 
C)  65.7 W 
D)  68.4 W 
E)  64.8 W

Question 5

A brass rod is 40.1 cm long and an aluminum rod is 79.3 cm long when both rods are at an initial temperature of 0°C.The rods are placed in line with a gap of 0.60 cm between them,as shown in the figure.The distance between the far ends of the rods is maintained at 120.0 cm throughout.The temperature of both rods is raised until the two rods are barely in contact.The coefficients of linear expansion of brass and aluminum are 2.0 × 10-5 K-1 and   ,respectively.The temperature at which contact of the rods barely occurs is closest to

Accepted Answer

A)  220°C. 
B)  210°C. 
C)  200°C. 
D)  230°C. 
E)  240°C. 
A)  220°C. 
B)  210°C. 
C)  200°C. 
D)  230°C. 
E)  240°C.

Question 6

The filament in a light bulb has a diameter of 0.050 mm and an emissivity of 1.0.The temperature of the filament is 3000°C.What should be the length of the filament so it will radiate 60 W of power? The Stefan-Boltzmann constant is   .

Accepted Answer

A)  11 cm 
B)  9.4 cm 
C)  8.6 cm 
D)  7.2 cm 
E)  5.9 cm 
A)  11 cm 
B)  9.4 cm 
C)  8.6 cm 
D)  7.2 cm 
E)  5.9 cm

Question 7

A chunk of ice (T = -20°C)is added to a thermally insulated container of cold water (T = 0°C).What happens in the container?

Accepted Answer

A)  The ice melts until thermal equilibrium is established. 
B)  The water cools down until thermal equilibrium is established. 
C)  Some of the water freezes and the chunk of ice gets larger. 
D)  None of the above things happen. 
A)  The ice melts until thermal equilibrium is established. 
B)  The water cools down until thermal equilibrium is established. 
C)  Some of the water freezes and the chunk of ice gets larger. 
D)  None of the above things happen.

Question 8

A cube at 100°C radiates heat at a rate of 80.0 J/s.If its surface temperature is increased to 200°C,the rate at which it will now radiate is closest to

Accepted Answer

A)  160 J/s. 
B)  207 J/s. 
C)  320 J/s. 
D)  640 J/s. 
E)  1280 J/s. 
A)  160 J/s. 
B)  207 J/s. 
C)  320 J/s. 
D)  640 J/s. 
E)  1280 J/s.

Question 9

What is the steady state rate of heat flow through a pane of glass that is 40.0 cm by 30.0 cm with a thickness of 4.00 mm when the outside temperature of the glass is -10.0°C and its inside temperature is 25.0°C? The thermal conductivity of glass is 0.105 W/(m • K),the specific heat of glass is 0.180 cal/(g • °C),and 1 cal = 4.190 J.

Accepted Answer

A)  24.2 W 
B)  3.81 W 
C)  18.6 W 
D)  47.3 W 
E)  110 W 
A)  24.2 W 
B)  3.81 W 
C)  18.6 W 
D)  47.3 W 
E)  110 W

Question 10

If the temperature of an iron sphere is increased

Accepted Answer

A)  its density will increase. 
B)  its volume will decrease. 
C)  its density will decrease. 
D)  its mass will decrease. 
E)  its density will remain unchanged. 
A)  its density will increase. 
B)  its volume will decrease. 
C)  its density will decrease. 
D)  its mass will decrease. 
E)  its density will remain unchanged.

Question 11

A spherical object 25.0 cm in diameter having an emissivity of 0.800 is held at a temperature of 275°C by an internal heater.This object is embedded in a very large vat of water at 100.0°C and atmospheric pressure.At what maximum rate (in g/min)is the water evaporating in the vat due to the radiated heat it receives from the object? You can ignore any heat radiated by the water.The latent heat of fusion for water is 33,400 J/kg,its latent heat of vaporization is   ,and the Stefan-Boltzmann constant is   .

Accepted Answer

The answer of A spherical object 25.0 cm in diameter...

Question 12

An 80-g aluminum calorimeter contains 380 g of water at an equilibrium temperature of 20°C.A   piece of metal,initially at   is added to the calorimeter.The final temperature at equilibrium is 32°C.Assume there is no external heat exchange.The specific heats of aluminum and water are 910 J/kg • K and 4190 J/kg • K,respectively.The specific heat of the metal is closest to

Accepted Answer

A)  520 J/kg • K. 
B)  480 J/kg • K. 
C)  390 J/kg • K. 
D)  350 J/kg • K. 
E)  560 J/kg • K. 
A)  520 J/kg • K. 
B)  480 J/kg • K. 
C)  390 J/kg • K. 
D)  350 J/kg • K. 
E)  560 J/kg • K.

Question 13

You want to insert an aluminum rod,which at 20°C has a radius of 1.000200 cm into a copper tube which has a radius of 1.000100 cm at the same temperature.You decide to put both of them in the refrigerator.At what temperature will the rod just fit if both are cooled to the same temperature? The coefficient of thermal expansion for aluminum is   ,and that of copper is 1.7 ×     .

Accepted Answer

A)  7.8°C 
B)  6.3°C 
C)  9.2°C 
D)  15°C 
E)  5.7°C 
A)  7.8°C 
B)  6.3°C 
C)  9.2°C 
D)  15°C 
E)  5.7°C

Question 14

A 406.0 kg copper bar is put into a smelter for melting.The initial temperature of the copper is 300.0 K.How much heat must the smelter produce to completely melt the copper bar? (The specific heat for copper is 386 J/kg • K,the heat of fusion for copper is   ,and its melting point is 1357 K.)

Accepted Answer

A)  2.49 × 105 kJ 
B)  1.66 × 1011 kJ 
C)  1.66 × 108 kJ 
D)  2.96 × 105 kJ 
A)  2.49 × 105 kJ 
B)  1.66 × 1011 kJ 
C)  1.66 × 108 kJ 
D)  2.96 × 105 kJ

Question 15

Two experimental runs are performed to determine the calorimetric properties of an alcohol that has a melting point of -10°C.In the first run,a 200-g cube of frozen alcohol,at the melting point,is added to 300 g of water at 20°C in a styrofoam container.When thermal equilibrium is reached,the alcohol-water solution is at a temperature of 5.0°C.In the second run,an identical cube of alcohol is added to 500 g of water at 20°C and the temperature at thermal equilibrium is 10°C.The specific heat of water is 4190 J/kg • K.Assume that no heat is exchanged with the styrofoam container and with the surroundings.The heat of fusion of the alcohol is closest to

Accepted Answer

A)  5.5 × 104 J/kg. 
B)  6.3 × 104 J/kg. 
C)  7.1 × 104 J/kg. 
D)  7.9 × 104 J/kg. 
E)  8.7 × 104 J/kg. 
A)  5.5 × 104 J/kg. 
B)  6.3 × 104 J/kg. 
C)  7.1 × 104 J/kg. 
D)  7.9 × 104 J/kg. 
E)  8.7 × 104 J/kg.

Question 16

A solid metal sphere is 15.0 cm in diameter and has surface of uniform color.When its surface is at 112°C,you measure that it radiates energy at a rate of 71.3 W.What is the emissivity of the surface of this object? Any heat that enters the sphere from the outside environment is negligible.The Stefan-Boltzmann constant is

Accepted Answer

The answer of A solid metal sphere is 15.0 cm...

Question 17

A cylindrical bar that us well insulated around its sides connects hot and cold reservoirs and conducts heat at a rate of 10.0 J/s under steady state conditions.If all of its linear dimensions (diameter and length)are reduced by half,the rate at which it will now conduct heat between the same reservoirs is closest to

Accepted Answer

A)  80.0 J/s. 
B)  20.0 J/s. 
C)  5.00 J/s. 
D)  2.50 J/s. 
E)  1.25 J/s. 
A)  80.0 J/s. 
B)  20.0 J/s. 
C)  5.00 J/s. 
D)  2.50 J/s. 
E)  1.25 J/s.

Question 18

A copper cylinder with a mass of 125 g and temperature of 345°C is cooled by dropping it into a glass beaker containing 565 g of water initially at 20.0°C.The mass of the beaker is 50.0 g and the specific heat of the glass is 840 J/kg • K.What is the final equilibrium temperature of the system,assuming the cooling takes place very quickly,so that no energy is lost to the air? The specific heat of copper is 385 J/kg • K and that of water is 4190 J/kg • K.

Accepted Answer

The answer of A copper cylinder with a mass of...

Question 19

It is a well-known fact that water has a higher specific heat than iron.Now,consider equal masses of water and iron that are initially in thermal equilibrium.The same amount of heat,30 calories,is added to each one.Which statement is true?

Accepted Answer

A)  They remain in thermal equilibrium. 
B)  They are no longer in thermal equilibrium; the iron is warmer. 
C)  They are no longer in thermal equilibrium; the water is warmer. 
D)  It is impossible to say without knowing the exact mass involved. 
E)  It is impossible to say without knowing the exact specific heats. 
A)  They remain in thermal equilibrium. 
B)  They are no longer in thermal equilibrium; the iron is warmer. 
C)  They are no longer in thermal equilibrium; the water is warmer. 
D)  It is impossible to say without knowing the exact mass involved. 
E)  It is impossible to say without knowing the exact specific heats.

Question 20

A person pours 330 g of water at 45°C into an 855-g aluminum container with an initial temperature of 10°C.The specific heat of aluminum is   and that of water is   .What is the final temperature of the system,assuming no heat is exchanged with the surroundings?

Accepted Answer

A)  28°C 
B)  32°C 
C)  31°C 
D)  33°C 
E)  35°C 
A)  28°C 
B)  32°C 
C)  31°C 
D)  33°C 
E)  35°C

Exam 17: Temperature and Heat

A cube at 100.0°C radiates heat at a rate of 80.0 J/s.If the length of each side is cut in half,the rate at which it will now radiate is closest to

A blacksmith is flattening a steel plate that measures .He has heated the plate to 900 K.If the emissivity of the plate is 0.75,what is the total rate at which it radiates energy? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 • K4.Ignore any heat it receives from the surroundings.

If 2.0 g of water at 0.00°C is to be vaporized,how much heat must be added to it? The specific heat of water is 1.0 cal/g • K,its heat of fusion is 80 cal/g,and its heat of vaporization is .

What is the net power that a person loses through radiation if her surface area is 1.20 m2,if her emissivity is 0.895,if her skin temperature is 300 K,and if she is in a room that is at a temperature of 17°C? The Stefan-Boltzmann constant is 5.670 × 10-8 W/m2 • K4.

The filament in a light bulb has a diameter of 0.050 mm and an emissivity of 1.0.The temperature of the filament is 3000°C.What should be the length of the filament so it will radiate 60 W of power? The Stefan-Boltzmann constant is .

A chunk of ice (T = -20°C)is added to a thermally insulated container of cold water (T = 0°C).What happens in the container?

A cube at 100°C radiates heat at a rate of 80.0 J/s.If its surface temperature is increased to 200°C,the rate at which it will now radiate is closest to

If the temperature of an iron sphere is increased

A 406.0 kg copper bar is put into a smelter for melting.The initial temperature of the copper is 300.0 K.How much heat must the smelter produce to completely melt the copper bar? (The specific heat for copper is 386 J/kg • K,the heat of fusion for copper is ,and its melting point is 1357 K.)

It is a well-known fact that water has a higher specific heat than iron.Now,consider equal masses of water and iron that are initially in thermal equilibrium.The same amount of heat,30 calories,is added to each one.Which statement is true?

A person pours 330 g of water at 45°C into an 855-g aluminum container with an initial temperature of 10°C.The specific heat of aluminum is and that of water is .What is the final temperature of the system,assuming no heat is exchanged with the surroundings?

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Filters

A blacksmith is flattening a steel plate that measures .He has heated the plate to 900 K.If the emissivity of the plate is 0.75,what is the total rate at which it radiates energy? The Stefan-Boltzmann constant is 5.670 × 10^-8 W/m² • K⁴.Ignore any heat it receives from the surroundings.

What is the net power that a person loses through radiation if her surface area is 1.20 m²,if her emissivity is 0.895,if her skin temperature is 300 K,and if she is in a room that is at a temperature of 17°C? The Stefan-Boltzmann constant is 5.670 × 10^-8 W/m² • K⁴.