#  Thermodynamics 

 



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### Joule's Experiment

\[M | t++ | —\]  
Falling mass turns paddle wheel in honey raising its temperature.

### Bag of Lead Shot

\[M | t | ★\]  
Dropping bag containing lead turns gravitational potential energy to heat.  
  
\[[In-Depth Description](/presentations/bag-lead-shot)\]

### Friction Heating

\[M | t | —\]   
Boy scout trick, rubbing metal rod with rope heats rod.

### Adiabatic Heating with Syringe

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Compression of gas within syringe heats gas and ignites cotton.

### Adiabatic Heating

\[M | t+ | ★\]  
Compression of gas within bicycle pump heats gas; alternatively, syringe PV=nRT (w/ Mac TC read-out).  
  
\[[In-Depth Description](/presentations/adiabatic-heating)\]

### Stirling Cycle Engine

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Hot air external combustion engine.

### Vortex Tube

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This clever tube separates hot and cold air out of a jet of room temperature air and serves as a refrigerator.

\[[In-Depth Description](/presentations/vortex-tube)\]

### Maxwell's Demon

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Black and white balls, rolling around in a glass flask, are seemingly segregated by Maxwell's demon to decrease entropy.

### Thermoelectric Motor

\[S | t+ | —\]   
Two different temperature heat reservoirs power the motor - it's not how hot it is that counts but rather the temperature difference.

### Steam Engine

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Small steam engine to drive external dynamo and lamp.

### Archibald Rubber Band Engine

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Differential expansion and contraction of rubber bands turns wheel half-immersed in hot water.

### Increasing Entropy

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Two, sealed, connected, glass flasks contain smoky air and a vacuum respectively; opening the connecting valve increases the entropy of the system.

### Videotape Entropy

\[M | t+ | —\]   
Watch entropy increase with repeated re-recordings.

### Mixing and Unmixing

\[M | t+ | ★★★\]  
Food coloring in glycerine is mixed by turning a drum, then unmixed by reversing. Has entropy *decreased*?  
  
\[[In-Depth Description](/presentations/mixing-and-unmixing)\]

### Contact Us

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**Campus Location**: Science Center B-08A | **Tel**: (617) 495-5824 | **Email**: scidemos-at-fas.harvard.edu