Modern Engineering Thermodynamics

Problems 725
the officer asks Paul for the value of his experimental LTN,
promising to release him if his answer is correct. Paul replies,
“0.29, sir.” The officer then consults the state patrolman’s guide
to locomotion transport numbers for the correct value. Does
Paul get arrested?
47.* Tom is a 75.0 kg bicyclist who recently averaged 42.0 km/h
during a 240. km race with an 8.40 kg racing bike. If he
consumes 4100. L of oxygen and has a muscle energy
conversion efficiency of 25.0%, determine
a. His rate of conversion of oxygen in L/min.
b. His locomotion transport number.
48. Sharla, weighing 140. lbf, absorbs 0.500 hp in her muscles
while pedaling a 7.00 lbf bicycle at 25.0 mph into a 5.00 mph
head wind in air at 70.0°F. Her frontal cross-section is 4.00 ft by
2.00 ft, and her drag coefficient is 0.500.
a. Compute her locomotion transport number.
b. Determine her most efficient velocity on the bicycle.
49.* Jim has a frontal cross-section of 2.00 m high by 0.500 m wide
and can run at 4.00 m/s and swim at 1.00 m/s. His drag
coefficients in air and water are 1.30 and 1.10, respectively.
What speeds should Jim run and swim at to be most efficient?
Assume Jim’s BMR is 0.300 MJ/h.
50.* Determine which of the following expends the most energy over
a 20.0 mi course:
a. A 126 kg pedal-powered aircraft flying at a speed of
15.0 mph with a locomotion transport number of 0.134.
b. A fast walking 75.0 kg person walking at a speed of
2.50 mph,
c. Determine the energy expenditure rates of the person
powering the aircraft and the person walking and comment
on the feasibility of maintaining these rates over the 20.0 mi
course.
51. If King Kong was ten times bigger than a normal human being,
a. Find his locomotion transport number while riding a bicycle
(assume his bicycle locomotion transport number is 25.0%
of the minimum value shown on Figure 17.12).
b. What was his most efficient walking velocity (assume the
same drag coefficient as for a human).
52. Convert the k d /α information associated with Eq. (17.33) from
metric units into Engineering English units.
53.* If a cold-blooded animal has an activation entropy of death of
3088 kJ/(kgmole · K) at 25.0°C, what is the change in k d /α for
the animal if it moves to an environment at 20.0°C?
54.* If the specific molar activation enthalpy of death is 800. MJ/
kgmole, the compensation temperature is 330. K, and the
constant β = −276 kJ/ðkgmole.KÞ, determine the specific molar
activation entropy of death.
Design Problems
The following are open-ended design problems. The objective is to
carryoutapreliminarydesignasindicated. A detailed design with
working drawings is not required unless otherwise specified by your
instructor. These problems have no specific answers, so each student’s
design is unique.
55. Design an inexpensive apparatus that measures the energy
conversion efficiency of an in vivo human arm or leg muscle.
Measure the oxygen consumption rate of the test subject to
determine the energy input rate. Include proper transducer
instrumentation for the necessary input data, and specify
adequate output electronics. Provide assembly and detailed
drawings sufficient to allow a technician to fabricate, assemble,
and test your design.
56. One of the problems with the commercially available bomb
calorimeters is that they can test only small samples on the
order of a few grams. Design a bomb calorimeter large enough
to burn a sample as large as 1 pound. Pay special attention to
safety considerations in your design. Do not attempt to
construct or test your design.
57. Design a system that measures the rate of metabolic
heat production of a small warm-blooded animal. You may
use either a direct or an indirect calorimetry technique.
Provide engineering drawings and instrumentation
specifications.
58. Design a whole body calorimeter that measures the
instantaneous metabolic heat loss rate from an entire human
body. Your system must be large enough or else sufficiently
mobile that measurements can be made while the test
subject is doing physical labor without restraint from your
system.
59. Design a variable resistance rowing exercise machine that has a
direct digital readout of the instantaneous energy expenditure
rate of the user. This means you have to specify or design
transducers that measure the instantaneous work rate (i.e.,
power) done on the machine. This power can be absorbed by
the machine either electrically or mechanically. Provide
assembly and detail drawings of your design plus specify all the
electronics necessary to process the transducer signals and
provide the proper digital output.
60. Design an apparatus that measures the metabolic heat loss rate
and surface temperature of a yeast culture or a small insect at
various environmental temperatures. Construct and calibrate this
apparatus if possible, and make enough measurements to plot
_Q /T b for some living system vs. time at various environmental
temperatures. Does _Q /T b increase or decrease as the
environmental temperature decreases?
Computer Problems
The following open-ended computer problems are designed to be
done on a personal computer using a spreadsheet, equation solver,
or programming language.
61. Develop an interactive computer program that returns the user’s
basal metabolic rate, oxygen uptake rate, carbon dioxide
production rate, pulse rate, and breathing rate when the user
inputs his or her mass or weight.
62. Develop an interactive computer program that outputs
the energy conversion efficiency of a person or an animal.
The user must be prompted for input data regarding work
performed, energy output resulting in increases in potential
or kinetic energies, and changes in body total internal
energy. You may assume that the specific internal energy of
the body is constant for activities that occur over short time
periods.
63. Develop an interactive computer program that provides the user
with the metabolizable energy content of foods chosen from a
menu. Allow the user to specify the desired energy units
(Calories, Btu, MJ) of the output.