PASCO TD-8592 SMALL PISTON HEAT ENGINE APPARATUS - Manual (Page 16)

012-08375A Small Piston Heat Engine
11
Experiment 5: The Mass Lifter Heat Engine 1
1 Priscilla W. Laws, et al. Workshop Physics Activity Guide, 1996 by John Wiley & Sons, Inc.
Reprinted by permission of John Wiley & Sons, Inc.
Your working group has been approached by the Newton Apple Company about testing a heat engine that lifts
apples that vary in mass from 50 g to 100 g from a processing conveyer belt to the packing conveyer belt that is
10 cm higher. The engine you are to experiment with is a "real" thermal engine that can be taken through a
four-stage expansion and compression cycle and that can do useful mechanical work by lifting small masses
from one height to another. In this experiment, we would like you to verify experimentally that the useful
mechanical work done in lifting a mass, m, through a vertical distance, y, is equal to the net thermodynamic
work done during a cycle as determined by finding the enclosed area on a P-V diagram. Essentially you are
comparing useful mechanical “ma
g
y” work (which we hope you believe in and understand from earlier studies)
with the accounting of work in an engine cycle as a function of pressure and volume changes given by the
expression:
Although you can prove mathematically that this relationship holds, the experimental verification will allow you
to become familiar with the operation of a real heat engine.
W
net
= PdV
Optional:
•
A computer-based laboratory system with barometer sensor
Equipment Required:
• Small Piston Heat Engine (1)
• Beakers (2), 1000 ml (to use as reservoirs)
• Ruler (1)
• Barometer pressure gauge (1)
• Calipers (1 set)
• Mass set, 20 g, 50 g, 100 g, 200 g
• Hot plate(1)
• Vat to catch water spills (1)
Figure 5.1. Doing useful mechanical
work by lifting a mass,
m, through a
height, y.
Figure 5.2 Doing thermodynamic
work in a heat engine cycle.
m
y
0
m
b c
d a
V
P
The Small Piston Heat Engine is ideal for use in the calculus-based experiment 18.10 of the Workshop
Physics Activity Guide. Following is a slightly modified reprint of the experiment: