p-v diagrams and processes c ontents: basic concept example whiteboards

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P-V Diagrams and processes Contents: Basic Concept Example Whiteboards

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P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards. Isobaric Expansion (+ W). Isobaric Compression (- W). Volume. Pressure. P-V diagrams. Iso = same baric = pressure. The axes Change volume? Change pressure?. TOC. Volume. Isochoric = same volume - PowerPoint PPT Presentation

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Page 1: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

P-V Diagrams and processesContents:• Basic Concept• Example• Whiteboards

Page 2: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

P-V diagrams

TOC

The axesChange volume?Change pressure?

Volume

Pres

sure

Isobaric Expansion (+W)

Isobaric Compression (-W)

Iso = samebaric = pressure

Page 3: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

P-V diagrams

TOC

Volume

Pres

sure

Isochoric = same volume(closed container)how does it happen?

Page 4: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Adiabatic (no heat flow) processes

TOC

Volume

Pres

sure

Adiabatic expansion: (Q = 0)Work is done by the gas (+W)No heat flows in: Q = U + W0 = U + W, U = -WInternal energy (T) drops

ExamplesAir rocketsCold side of fridgeUniverseDemo - cloud

Page 5: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards
Page 6: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Adiabatic (no heat flow) processes

TOC

Volume

Pres

sure

Adiabatic compression: (Q = 0)Work is done on the gas (-W)No heat flows in: Q = U + W0 = U + W, U = -(-W)Internal energy (T) rises

ExamplesBike pump/dieselsHot side of fridgeCompressorsDemo – plunger/Murray Frig

Page 7: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards
Page 8: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Isothermal (constant temperature) processes

TOC

Volume

Pres

sure

Isothermal expansion: (T = 0)Work is done by the gas (+W)Internal energy is constant (U = 0)Q = U + W = W Heat turns to work (slowly)

Page 9: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Isothermal (constant temperature) processes

TOC

Volume

Pres

sure

Isothermal compression: (T = 0)Work is done on the gas (-W)Internal energy is constant (U = 0)Q = U + W = W Work turns to heat (slowly)

Page 10: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

What’s goin’ on here?

TOC

Volume

Pres

sure

isobaric expansionheat flows in, temp increases

Page 11: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

What’s goin’ on here?

TOC

Volume

Pres

sure

isochoric coolingheat flows out, pressure drops

Page 12: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

What’s goin’ on here?

TOC

Volume

Pres

sure

isochoric heating, isobaric expansion

Page 13: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Which process is adiabatic, which is isothermal?

TOC

Volume

Pres

sure

In which process would the temperature drop?B is adiabatic

AB

Page 14: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

Which process is adiabatic, which is isothermal?

TOC

Volume

Pres

sure

In which process would the temperature increase?B is adiabatic

A

B

Page 15: P-V Diagrams and processes C ontents: Basic Concept Example Whiteboards

A complete cycle:

TOC

Volume

Pres

sure

Complete cycle - where is work done?Is more work done by gas or on the gas?

A

B C

D