Interactive
Lecture Demonstrations
Prediction
Sheet— Heat Engine
Directions: Click here to download the Prediction Sheet. Write
your name at the top to record your presence and participation in these
demonstrations. Record your
predictions before making any observations. Your instructor may ask you to send
in this sheet.
You
can click here to view a photo of the heat
engine apparatus.
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Make your
predictions for 1a through 1d on the axes above before observing the
video. Demonstration
1a: The cycle of the engine begins with the
flask in the COLD reservoir, and the 100 gram mass off
of the piston. This state is
represented by the black dot on the axes above. Sketch on the axes the process that takes place
when the mass is quickly put on top of the piston, with the flask left in the
COLD reservoir. Describe in words what
happens to the pressure and the volume of the air in the syringe. Demonstration
1b:
In the next process of the cycle, the flask is moved from the COLD reservoir
to the HOT reservoir, with the mass left on top of the piston. Sketch this
process on the axes. Describe in words
what happens to the pressure and the volume of the air in the syringe. Demonstration
1c:
In the next process of the cycle, the mass is removed from the top of the
piston, with the flask left in the HOT reservoir. Sketch this process on the
axes. Describe in words what happens to the pressure and the volume of the
air in the syringe. Demonstration
1d: In the last process of the cycle, the flask
is moved from the HOT reservoir back to the COLD reservoir with the mass
removed from the top of the piston. Sketch this process on the axes. Describe
in words what happens to the pressure and the volume of the air in the
syringe. Only after you have made all of
these predictions, click here to download
and view the video of the operation of the heat engine. (Note that the volume
for each of the steps a through d is read from the syringe and beaker and
entered manually at each step.) Compare your
predictions to your observations on the video and explain any differences. Approximately
what type of process (isobaric, isovolumetric, isothermal, or adiabatic) is
each of the steps a through d? Explain each. a: b: c: d: Only after you have made your predictions, click here to view what types of processes were involved
in the operation of the heat engine. |
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Demonstration
2: How could you calculate the work done by
the gas during this cycle? Show on your P-V diagram what represents the work
done during the cycle. Only
after you have made your prediction, click here
to observe how work is calculated on a P-V diagram. Explain how it is done. |
