PASCO TD-8592 SMALL PISTON HEAT ENGINE APPARATUS - Manual (Page 18)

012-08375A Small Piston Heat Engine
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Figure 5.4. A simplified diagram of the mass lifter heat engine at different stages of its cycle
of a cycle carefully, indicating which of the transitions between points are approximately adia-
batic and which are isobaric. You can observe changes in the volume of the gas directly and you
can predict how the pressure exerted on the gas by its surroundings ought to change from point to
point by using the definition of pressure as force per unit area.
5.1 Activity: Description of the Engine Cycle
a. Predicted transition a ➔ b: Close the system to outside air but leave the can in the cold reservoir.
Make sure the rubber stopper is firmly in place in the can. What should happen to the height of
the platform when you add a mass? Explain the basis of your prediction.
b. Observed transition a ➔ b: What happens when you add the mass to the platform? Is this what
you predicted?
c. Predicted transition b ➔ c: What do you expect to happen when you place the can in the hot
reservoir ?
d. Observed transition b ➔ c: Place the can in the hot reservoir and describe what happens to
the platform with the added mass on it. Is this what you predicted? (This is the engine
power stroke!)
m
y y
m
0 0 0
m
m
Point A Point B Point C Point D
Cold Cold Hot Hot