Thermodynamics Concepts and Applications

The lecture introduces thermodynamics, focusing on the first and second laws. The first law relates to the conservation of energy, while the second law addresses the direction of heat transfer and efficiency limits. Examples illustrate these concepts, including calculations of internal energy changes and heat engine efficiency. The lecture also covers PV diagrams, reversible processes, and the limitations of converting heat to work.

What does the first law of thermodynamics state about the change in internal energy of a system?

• It is equal to the net heat transfer into the system plus the net work done on the system.

• It is equal to the net heat transfer into the system minus the net work done on the system.

• It is equal to the net heat transfer out of the system plus the net work done on the system.

• It is equal to the net work done on the system minus the net heat transfer into the system.

In the example calculation, what is the net heat transfer into the system?

• 10 Joules

• 40 Joules

• 25 Joules

• 15 Joules

What is the net work done on the system in the example calculation?

• 9 Joules

• 10 Joules

• 6 Joules

• 4 Joules

What is a heat engine?

• A device that stores heat energy.

• A device that uses mechanical energy to produce heat.

• A device that uses heat energy to do work.

• A device that converts thermal energy into electrical energy.

In a PV diagram, what does a horizontal path represent?

• Constant volume

• Constant pressure

• Changing volume

• Changing pressure

What is the work done along a vertical path in a PV diagram?

• Equal to the change in volume multiplied by the change in pressure

• Zero

• Equal to the change in pressure multiplied by the volume

• Equal to the pressure multiplied by the change in volume

What is a reversible process?

• A process where the system and environment can return to their original states by following the reverse path.

• A process where the system can only move in one direction.

• A process that is 100% efficient.

• A process that involves no heat transfer.

According to the second law of thermodynamics, what is required to transfer heat from a cool object to a hot one?

• It requires a temperature gradient.

• It happens spontaneously.

• Work must be done.

• No work is required.

What is the efficiency of a system if Qc is zero?

• 0%

• 50%

• 75%

• 100%

In the coal power plant example, what is the efficiency of the plant?

• 50.8%

• 30.8%

• 40.8%

• 60.8%