Practice question · Sort into groups
Sort each expression by the kind of system whose work it describes.
Groups: A fluid changing volume · A surface changing area · An electrical cell
- Surface tension times change in area
- Minus pressure times change in volume
- EMF times charge transferred
Hints
- Each has the form intensive variable times change in extensive variable.
- Match the intensive variable to the system it belongs to.
Show the answer
A fluid changing volume: Minus pressure times change in volume
A surface changing area: Surface tension times change in area
An electrical cell: EMF times charge transferred
Why
Every work term pairs an intensive variable with the change in its extensive partner: with , surface tension with area, EMF with charge. The pattern is universal even though the physics differs.
Practise Work and the Joule Experiment
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