PASCO TD-8572 HEAT ENGINE_ GAS LAW APPARATUS - Manual (Page 15)

012-06014C Heat Engine/Gas Law Apparatus
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.
The Heat Engine/Gas Law Apparatus 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:
Your working group has been approached by the Newton Apple Company about testing a
heat engine that lifts apples that vary in mass from 100 g to 200 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 expan-
sion 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 experi-
mentally 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 me-
chanical “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:
• Heat Engine/Gas Law Apparatus
• 2 Pyrex beakers, 1000 ml (to use as reservoirs)
• 1 ruler
• 1 barometer pressure gauge
• 1 calipers
• 1 mass set, 20 g, 50 g, 100 g, 200 g
• 1 hot plate
• 1 vat to catch water spills
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