B.4 Thermodynamic Processes

• Yes, is greater than 30%

• No, it's greater than 30%

• No, it's greater than 67%

• Yes, it's greater than 67%

Answer explanation

Quoted efficiency = 35%

Calculated Carnot efficiency = 30%

Answer: NO

impossible to reach efficiency greater than 30%

Which process is adiabatic?

• X-A

• X-B

• X-C

• X-D

Answer explanation

ADIABATIC EXPANSION

ponint X starts in a hot Temperature.

point D ends in a lower temperature.

There was no transfer of heat between gas and surroundings.

Which process is Isovolumetric?

• X-A

• X-B

• X-C

• X-D

Answer explanation

ISOVOLUMETRIC

point X starts in a hot Temperature.

point B ends in a lower temperature.

Pressure decreases.

If ∆V=0 then WorkDone=0

Which process is Isobaric?

• X-A

• X-B

• X-C

• X-D

Answer explanation

ISOBARIC EXPANSION

point X starts in a LOW Temperature.

point A ends in a HIGHER temperature.

Pressure is constant.

If ∆p=0 but there is WorkDone (+∆V)

Which process is Isothermal?

• X-A

• X-B

• X-C

• X-D

Answer explanation

ISOTHERMAL EXPANSION

point X starts in a hot Temperature.

point C ends in a lower temperature.

Pressure decreases.

If ∆T=0 then ∆U=0 (internal energy)

Which of the following statements best describes the First Law of Thermodynamics? A) Energy cannot be created or destroyed, only converted from one form to another. B) Entropy of an isolated system always increases. C) Temperature of a system always decreases as heat flows out of it. D) The work done by a system is equal to the energy input into the system.

• A

• B

• C

• D

Answer explanation

Q: transfer of thermal eneergy.

∆U: change in internal energy (related to change in temperature)

W: work done (related to ∆Volume)

A gas is slowly compressed by a piston, causing its volume to decrease. Which of the following is true according to the First Law of Thermodynamics?

• The internal energy of the gas increases.

• The internal energy of the gas decreases.

• The work done on the gas is negative.

• The heat added to the gas is negative.

Answer explanation

A gas is slowly compressed by a piston

if it's slowly ... no change in temperature but it's difficult to achieve it in real life.

What is the name of the missing thermodynamic process?

• Adiabatic compression

• Adiabatic Expansion

• Isobaric compression

• Isobaric expansion

Answer explanation

Adiabatic = Q = 0

The P–V diagram of the Carnot cycle for a monatomic ideal gas is shown.

Identify the isothermal compression

• A-B

• B-C

• C-D

• D-A

The P–V diagram of the Carnot cycle for a monatomic ideal gas is shown.

Identify the compression where Q=0 J

• A-B

• B-C

• C-D

• D-A