Question 1

Steel blocks A and B, which have equal masses, are at TA = 300 °C and TB = 400 °C. Block C, with mC = 2mA, is at TC = 350 °C. Blocks A and B are placed in contact, isolated, and allowed to come into equilibrium. Then they are placed in contact with block C. At that instant,

Accepted Answer

A)  TA = TB C. 
B)  TA = TB = TC. 
C)  TA = TB > TC. 
D)  TA + TB = TC. 
E)  TA − TB = TC.

Question 2

The Earth intercepts 1.27 × 1017 W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 × 1021 m3, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

Accepted Answer

A)  26.9 y 
B)  113 y 
C)  2.69 × 104 y 
D)  1.13 × 105 y 
E)  2.69 × 107 y

Question 3

If an object feels cold to the touch, the only statement that you can make that must be correct is that

Accepted Answer

A)  the object has a smaller coefficient of thermal conductivity than your hand. 
B)  the volume of the object will increase while it is in contact with your hand. 
C)  the object contains less thermal energy than your hand. 
D)  the object is at a lower temperature than your hand. 
E)  the object cannot be a liquid.

Question 4

Determine the heat capacity (in calories/°C) of a lake containing one million gallons (approximately 4 million kilograms) of water at 15°C.

Accepted Answer

A)  4 × 106 
B)  4 × 109 
C)  4 × 103 
D)  1 × 103 
E)  4 × 102

Question 5

The R value of fiberglass batting, 3.5 inches thick, is 11 ft2⋅°F⋅h/BTU. What is the thermal conductivity (in BTU/ft⋅°F⋅s)?

Accepted Answer

A)  7.4 × 10−6 
B)  2.7 × 10−2 
C)  8.9 × 10−5 
D)  1.4 × 10−4 
E)  3.6 × 10−3

Question 6

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the work done (in J). (The density of steam at 100°C is 0.598 kg/m3.)

Accepted Answer

A)  3.4 × 105 
B)  1.2 × 105 
C)  4.6 × 104 
D)  2.1 × 104 
E)  3.4 × 104

Question 7

Which statement below regarding the First Law of Thermodynamics is most correct?

Accepted Answer

A)  A system can do work externally only if its internal energy decreases. 
B)  The internal energy of a system that interacts with its environment must change. 
C)  No matter what other interactions take place, the internal energy must change if a system undergoes a heat transfer. 
D)  The only changes that can occur in the internal energy of a system are those produced by non-mechanical forces. 
E)  The internal energy of a system cannot change if the heat transferred to the system is equal to the work done by the system.

Question 8

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the change in internal energy (in J). (Lv = 2.26 × 106 J/kg.)

Accepted Answer

A)  2.1 × 104 
B)  4.5 × 106 
C)  3.4 × 105 
D)  4.2 × 106 
E)  2.1 × 106

Question 9

A 100-g cube of ice is heated from −120°C to +120°C. In which of the following processes is the greatest amount of energy absorbed by this material?

Accepted Answer

A)  warming ice to the melting point 
B)  melting the ice to become water 
C)  warming the resulting water 
D)  vaporizing the water to become steam 
E)  heating the steam

Question 10

An 8 000-kg aluminum flagpole 100-m long is heated by the sun from a temperature of 10°C to 20°C. Find the work done (in J) by the aluminum if the linear expansion coefficient is 24 × 10−6 (°C)−1. (The density of aluminum is 2.7 × 103 kg/m3 and 1 atm = 1.0 × 105 N/m2.)

Accepted Answer

A)  287 
B)  425 
C)  213 
D)  710 
E)  626

Question 11

We are able to define a mechanical equivalent for heat because

Accepted Answer

A)  some thermal energy can be converted into mechanical energy. 
B)  mechanical energy can be converted into thermal energy. 
C)  work can be converted into thermal energy. 
D)  some thermal energy can be converted into work. 
E)  all of the above can occur.

Question 12

Which of the following statements is(are) correct when an ideal gas goes from an initial to a final state in a single process?

Accepted Answer

A)  No work is done on or by the gas when the volume remains constant. 
B)  No energy is transferred into or out of the gas as heat transfer when the temperature remains constant. 
C)  The internal energy of the gas does not change when the pressure remains constant. 
D)  All the statements above are correct. 
E)  Only statements (a) and (b) above are correct.

Question 13

A 5-gallon container of water (approximately 20 kg) having a temperature of 212°F is added to a 50-gallon tub (approximately 200 kg) of water having a temperature of 50°F. What is the final equilibrium temperature (in °C) of the mixture?

Accepted Answer

A)  54 
B)  36 
C)  18 
D)  66 
E)  14

Question 14

A team of people who traveled to the North Pole by dogsled lived on butter because they needed to consume 6 000 dietician's Calories each day. Because the ice there is lumpy and irregular, they had to help the dogs by pushing and lifting the load. Assume they had a 16 hour working day and that each person could lift a 500 N load. How many times would a person have to lift this weight 1.00 m upwards in a constant gravitational field where  to do the work equivalent to 6 000 Calories?

Accepted Answer

A)  50.2 
B)  492 
C)  5 130 
D)  50 200 
E)  492 000

Question 15

A super-insulated house is at a temperature of 20°C. The temperature outside is 0°C. The surface area of the house is 200 m2, and the emissivity is 1. Approximately how much energy is radiated (in W) per second?

Accepted Answer

A)  20 000 
B)  2 000 
C)  200 
D)  2 
E)  0.2

Question 16

A 100-kg student eats a 200-Calorie doughnut. To "burn it off", he decides to climb the steps of a tall building. How high (in m) would he have to climb to expend an equivalent amount of work? (1 food Calorie = 103 calories.)

Accepted Answer

A)  273 
B)  623 
C)  418 
D)  854 
E)  8 400

Question 17

A child has a temperature of 101°F. If her total cross-sectional area is 2 m2, find the energy lost each second (in W) due to radiation, assuming the emissivity is 1. (Assume the room temperature is 70°F.)

Accepted Answer

A)  217 
B)  180 
C)  90 
D)  68 
E)  850

Question 18

In an isothermal process

Accepted Answer

A)  P is constant. 
B)  V is constant. 
C) 
 is constant. 
D)  PV is constant. 
E) 
 is constant.

Question 19

A gas expands from A to B as shown in the graph. Calculate the work (in joules) done by the gas. (1 atm= 1.01 × 105 N/m2.)

Accepted Answer

A)  12 
B)  24 
C)  1.21 × 106 
D)  2.42 × 106 
E)  3.64 × 106

Question 20

A cup of coffee is enclosed on all sides in an insulated container 1/2 cm thick in the shape of a cube 10 cm on a side. The temperature of the coffee is 95°C, and the temperature of the surroundings is 21°C. Find the rate of heat loss (in J/s) due to conduction if the thermal conductivity of the cup is 2 × 10−4 cal/s⋅cm⋅°C.

Accepted Answer

A)  62 
B)  74 
C)  230 
D)  160 
E)  12

Exam 20: The First Law of Thermodynamics

Steel blocks A and B, which have equal masses, are at T_A = 300 °C and T_B = 400 °C. Block C, with m_C = 2m_A, is at T_C = 350 °C. Blocks A and B are placed in contact, isolated, and allowed to come into equilibrium. Then they are placed in contact with block C. At that instant,

The Earth intercepts 1.27 × 10¹⁷ W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 × 10²¹ m³, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

If an object feels cold to the touch, the only statement that you can make that must be correct is that

Determine the heat capacity (in calories/°C) of a lake containing one million gallons (approximately 4 million kilograms) of water at 15°C.

The R value of fiberglass batting, 3.5 inches thick, is 11 ft²⋅°F⋅h/BTU. What is the thermal conductivity (in BTU/ft⋅°F⋅s) ?

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the work done (in J) . (The density of steam at 100°C is 0.598 kg/m³.)

Which statement below regarding the First Law of Thermodynamics is most correct?

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the change in internal energy (in J) . (L_v = 2.26 × 10⁶ J/kg.)

A 100-g cube of ice is heated from −120°C to +120°C. In which of the following processes is the greatest amount of energy absorbed by this material?

An 8 000-kg aluminum flagpole 100-m long is heated by the sun from a temperature of 10°C to 20°C. Find the work done (in J) by the aluminum if the linear expansion coefficient is 24 × 10−⁶ (°C) −¹. (The density of aluminum is 2.7 × 10³ kg/m³ and 1 atm = 1.0 × 10⁵ N/m².)

We are able to define a mechanical equivalent for heat because

Which of the following statements is(are) correct when an ideal gas goes from an initial to a final state in a single process?

A 5-gallon container of water (approximately 20 kg) having a temperature of 212°F is added to a 50-gallon tub (approximately 200 kg) of water having a temperature of 50°F. What is the final equilibrium temperature (in °C) of the mixture?

A super-insulated house is at a temperature of 20°C. The temperature outside is 0°C. The surface area of the house is 200 m², and the emissivity is 1. Approximately how much energy is radiated (in W) per second?

A 100-kg student eats a 200-Calorie doughnut. To "burn it off", he decides to climb the steps of a tall building. How high (in m) would he have to climb to expend an equivalent amount of work? (1 food Calorie = 10³ calories.)

A child has a temperature of 101°F. If her total cross-sectional area is 2 m², find the energy lost each second (in W) due to radiation, assuming the emissivity is 1. (Assume the room temperature is 70°F.)

In an isothermal process

A gas expands from A to B as shown in the graph. Calculate the work (in joules) done by the gas. (1 atm= 1.01 × 10⁵ N/m².)

Exam 20: The First Law of Thermodynamics

Steel blocks A and B, which have equal masses, are at TA = 300 °C and TB = 400 °C. Block C, with mC = 2mA, is at TC = 350 °C. Blocks A and B are placed in contact, isolated, and allowed to come into equilibrium. Then they are placed in contact with block C. At that instant,

The Earth intercepts 1.27 × 1017 W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 × 1021 m3, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

If an object feels cold to the touch, the only statement that you can make that must be correct is that

Determine the heat capacity (in calories/°C) of a lake containing one million gallons (approximately 4 million kilograms) of water at 15°C.

The R value of fiberglass batting, 3.5 inches thick, is 11 ft2⋅°F⋅h/BTU. What is the thermal conductivity (in BTU/ft⋅°F⋅s) ?

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the work done (in J) . (The density of steam at 100°C is 0.598 kg/m3.)

Which statement below regarding the First Law of Thermodynamics is most correct?

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the change in internal energy (in J) . (Lv = 2.26 × 106 J/kg.)

A 100-g cube of ice is heated from −120°C to +120°C. In which of the following processes is the greatest amount of energy absorbed by this material?

An 8 000-kg aluminum flagpole 100-m long is heated by the sun from a temperature of 10°C to 20°C. Find the work done (in J) by the aluminum if the linear expansion coefficient is 24 × 10−6 (°C) −1. (The density of aluminum is 2.7 × 103 kg/m3 and 1 atm = 1.0 × 105 N/m2.)

We are able to define a mechanical equivalent for heat because

Which of the following statements is(are) correct when an ideal gas goes from an initial to a final state in a single process?

A 5-gallon container of water (approximately 20 kg) having a temperature of 212°F is added to a 50-gallon tub (approximately 200 kg) of water having a temperature of 50°F. What is the final equilibrium temperature (in °C) of the mixture?

A super-insulated house is at a temperature of 20°C. The temperature outside is 0°C. The surface area of the house is 200 m2, and the emissivity is 1. Approximately how much energy is radiated (in W) per second?

A 100-kg student eats a 200-Calorie doughnut. To "burn it off", he decides to climb the steps of a tall building. How high (in m) would he have to climb to expend an equivalent amount of work? (1 food Calorie = 103 calories.)

A child has a temperature of 101°F. If her total cross-sectional area is 2 m2, find the energy lost each second (in W) due to radiation, assuming the emissivity is 1. (Assume the room temperature is 70°F.)

In an isothermal process

A gas expands from A to B as shown in the graph. Calculate the work (in joules) done by the gas. (1 atm= 1.01 × 105 N/m2.)

Steel blocks A and B, which have equal masses, are at T_A = 300 °C and T_B = 400 °C. Block C, with m_C = 2m_A, is at T_C = 350 °C. Blocks A and B are placed in contact, isolated, and allowed to come into equilibrium. Then they are placed in contact with block C. At that instant,

The Earth intercepts 1.27 × 10¹⁷ W of radiant energy from the Sun. Suppose the Earth, of volume 1.08 × 10²¹ m³, was composed of water. How long would it take for the Earth at 0°C to reach 100°C, if none of the energy was radiated or reflected back out into space?

The R value of fiberglass batting, 3.5 inches thick, is 11 ft²⋅°F⋅h/BTU. What is the thermal conductivity (in BTU/ft⋅°F⋅s) ?

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the work done (in J) . (The density of steam at 100°C is 0.598 kg/m³.)

Two kilograms of water at 100°C is converted to steam at 1 atm. Find the change in internal energy (in J) . (L_v = 2.26 × 10⁶ J/kg.)

An 8 000-kg aluminum flagpole 100-m long is heated by the sun from a temperature of 10°C to 20°C. Find the work done (in J) by the aluminum if the linear expansion coefficient is 24 × 10−⁶ (°C) −¹. (The density of aluminum is 2.7 × 10³ kg/m³ and 1 atm = 1.0 × 10⁵ N/m².)

A super-insulated house is at a temperature of 20°C. The temperature outside is 0°C. The surface area of the house is 200 m², and the emissivity is 1. Approximately how much energy is radiated (in W) per second?

A 100-kg student eats a 200-Calorie doughnut. To "burn it off", he decides to climb the steps of a tall building. How high (in m) would he have to climb to expend an equivalent amount of work? (1 food Calorie = 10³ calories.)

A child has a temperature of 101°F. If her total cross-sectional area is 2 m², find the energy lost each second (in W) due to radiation, assuming the emissivity is 1. (Assume the room temperature is 70°F.)

A gas expands from A to B as shown in the graph. Calculate the work (in joules) done by the gas. (1 atm= 1.01 × 10⁵ N/m².)