Question 1

The PV diagram of a cyclic process shows a curve that encloses an area.The work done by the heat engine,represented by the enclosed area,is positive when the path around the area proceeds in which of the following fashions?

Accepted Answer

A) clockwise 
B) counterclockwise 
C) It is always positive. 
D) It is always negative.

Question 2

During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room.If one cycle occurs every 10 s,how many minutes will it take to freeze 575 g of water,initially at 0°C? (Lv = 80 cal/g)

Accepted Answer

A) 69.7 min 
B) 1 390 min 
C) 139 min 
D) 87.1 min 
E) 836 min

Question 3

Six moles of an ideal gas, initially at 178 C, is compressed at a constant pressure of 2.00 atm to one-third its initial volume.
-What is the final temperature of the gas?

Accepted Answer

A) -123 °C 
B) 150 °C 
C) 27.6 °C 
D) -59.3 °C

Question 4

Consider a Carnot cycle starting at the state of highest pressure and smallest volume.Call the isothermal expansion from this state step 1,the adiabatic expansion which follows step 2,the isothermal compression that then follows step 3,and the adiabatic compression which returns the system to the initial state step 4.In which steps does the internal energy of the system increase?

Accepted Answer

A) 1 and 2 
B) 3 and 4 
C) 1 and 3 
D) 2 and 4

Question 5

In an isothermal process for an ideal gas system (where the internal energy doesn't change),which of the following choices best corresponds to the value of the work done on the system?

Accepted Answer

A) its heat intake 
B) twice its heat intake 
C) the negative of its heat intake 
D) twice the negative of its heat intake

Question 6

An athlete has a basal metabolic rate of 70.0 W. As she is working out, her metabolic rate increases by about 600 W. She eats one piece of buttered toast for breakfast, which has 145 Calories. She wants to work off the piece of toast.
-How long will it take if she works out?

Accepted Answer

A) 0.228 min 
B) 13.7 min 
C) 15.1 min 
D) 0.252 min

Question 7

A system is acted on by its surroundings in such a way that it receives 80 J of heat while simultaneously doing 20 J of work.What is its net change in internal energy?

Accepted Answer

A) 100 J 
B) 60 J 
C) zero 
D) −60 J 
E) −100 J

Question 8

On a PV diagram,2 curves are plotted,both starting at the same point (P1,V1)and both ending at the same increased volume (V2).One curve is for an isothermal process;the other is for an adiabatic process.Except for the common starting point,which curve is the upper one?

Accepted Answer

A) The isothermal process curve will always be the upper one. 
B) The adiabatic process curve will always be the upper one. 
C) Since they start at the same point and end at the same volume,they will coincide. 
D) The isothermal one will start out higher,but the adiabatic one will eventually cross it.

Question 9

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 400 K and 200 K will have what maximum efficiency?​

Accepted Answer

A) 50%. 
B) 50% 
C) 40% 
D) 45% 
E) 25%

Exam 12: The Laws of Thermodynamics

The PV diagram of a cyclic process shows a curve that encloses an area.The work done by the heat engine,represented by the enclosed area,is positive when the path around the area proceeds in which of the following fashions?

During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room.If one cycle occurs every 10 s,how many minutes will it take to freeze 575 g of water,initially at 0°C? (L_v = 80 cal/g)

Six moles of an ideal gas, initially at 178 C, is compressed at a constant pressure of 2.00 atm to one-third its initial volume. -What is the final temperature of the gas?

In an isothermal process for an ideal gas system (where the internal energy doesn't change) ,which of the following choices best corresponds to the value of the work done on the system?

An athlete has a basal metabolic rate of 70.0 W. As she is working out, her metabolic rate increases by about 600 W. She eats one piece of buttered toast for breakfast, which has 145 Calories. She wants to work off the piece of toast. -How long will it take if she works out?

A system is acted on by its surroundings in such a way that it receives 80 J of heat while simultaneously doing 20 J of work.What is its net change in internal energy?

On a PV diagram,2 curves are plotted,both starting at the same point (P₁,V₁) and both ending at the same increased volume (V₂) .One curve is for an isothermal process;the other is for an adiabatic process.Except for the common starting point,which curve is the upper one?

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 400 K and 200 K will have what maximum efficiency?

Exam 12: The Laws of Thermodynamics

The PV diagram of a cyclic process shows a curve that encloses an area.The work done by the heat engine,represented by the enclosed area,is positive when the path around the area proceeds in which of the following fashions?

During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room.If one cycle occurs every 10 s,how many minutes will it take to freeze 575 g of water,initially at 0°C? (Lv = 80 cal/g)

Six moles of an ideal gas, initially at 178 C, is compressed at a constant pressure of 2.00 atm to one-third its initial volume. -What is the final temperature of the gas?

In an isothermal process for an ideal gas system (where the internal energy doesn't change) ,which of the following choices best corresponds to the value of the work done on the system?

An athlete has a basal metabolic rate of 70.0 W. As she is working out, her metabolic rate increases by about 600 W. She eats one piece of buttered toast for breakfast, which has 145 Calories. She wants to work off the piece of toast. -How long will it take if she works out?

A system is acted on by its surroundings in such a way that it receives 80 J of heat while simultaneously doing 20 J of work.What is its net change in internal energy?

On a PV diagram,2 curves are plotted,both starting at the same point (P1,V1) and both ending at the same increased volume (V2) .One curve is for an isothermal process;the other is for an adiabatic process.Except for the common starting point,which curve is the upper one?

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 400 K and 200 K will have what maximum efficiency?​

During each cycle of operation a refrigerator absorbs 55.0 cal from the freezer compartment and expels 88.0 cal to the room.If one cycle occurs every 10 s,how many minutes will it take to freeze 575 g of water,initially at 0°C? (L_v = 80 cal/g)

On a PV diagram,2 curves are plotted,both starting at the same point (P₁,V₁) and both ending at the same increased volume (V₂) .One curve is for an isothermal process;the other is for an adiabatic process.Except for the common starting point,which curve is the upper one?

A heat engine operating between a pair of hot and cold reservoirs with respective temperatures of 400 K and 200 K will have what maximum efficiency?