PIRA 4F30.70 Heat Engine Cycles

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Photo of University of Texas at Austin's Demonstration:

Faculty Instructions:

  • Data collection with the lab computer is optional for this demonstration.
  • Begin by immersing the can in the cold bath.
  • Once it has reached equilibrium, the piston should still be about 2-3 cm from the bottom of the cylinder.
  • Now, place the mass on the piston and immediately immerse the can in the hot bath.
  • Observe the piston pushing the mass upward as the air expands.
  • Once it has reached equilibrium, remove the mass from the piston and move the can back into the cold bath.
  • Observe how the piston returns to its original position.

    • Concepts Conveyed:

  • This demo consists of a heat engine of air inside a cylinder which expands when immersed in hot water.
  • The expanding air pushes on a piston and does work by lifting a provided weight.
  • The cycle is completed by immersing the can in cold water, which returns the air pressure and volume to their initial states.

    • Demo Staff Instructions:

  • Ensure the mass hanger is attached with 35 g of mass. This acts as a counterweight for the piston.
  • Displace the piston 2-3 cm from the bottom of the cylinder.
  • Prepare a hot (~80 degrees C) and cold (lots of ice!!) bath.

    • Last Updated 2023 - University of Texas at Austin Physics Department - All Rights Reserved