Problems 293
whereTis the period of oscillation of the pendulum,
the time that it takes the pendulum to complete one
cycle. The distance between the pivot point and the
center of the mass of the suspended deadweight is rep-
resented byL.10.8. Do you think there is relationship between a person’s
height, weight, and foot size? If so, verify your answer.
Designers often learn from their natural surroundings;
do the bigger animals have bigger feet?
10.9. Calculate the pressure exerted by water on the hull of
a submarine that is cruising at a depth of 500 ft below
ocean level. Assume the density of the ocean water is
r1025 kg /m
3
.
10.10.Investigate the operation of pressure-measuring devices
such as manometers, Bourden tubes, and diaphragm pres-
sure sensors. Write a brief report discussing your findings.
10.11. Convert the following pressure readings from inches
of mercury units to psi and Pascal units:
a. 28.5 inHg
b. 30.5 inHg
10.12.Convert the following air pressure readings from
inH 2 O to psi and Pa.
a. 1.5 inH 2 O
b. 3.75 inH 2 O
10.13. A person with hypertension has a systolic /diastolic of
140/110 mmHg. Express these pressures in Pa, psi,
and inH 2 O.
10.14. If a pressure gauge on a compressed air tank reads
120 psi, assuming standard atmospheric pressure at sea
level, what is the absolute pressure of air in
a. psi
b. pascal
c. feet of water
d. feet of mercury
10.15. An air compressor intakes atmospheric air at 14.7 psi and
increases its pressure to 175 psi (gauge). The pressurized
air is stored in a horizontal tank. What is the absolute
pressure of air inside the tank? Express your answers in
a. psi
b. kPa
c. bar
d. standard atm (recall that 1 atm14.7 psi
101.325 kPa)
10.16.Calculate the pressure exerted by water on a scuba diver
who is swimming at a depth of 50 ft below the water
surface.
10.17. Investigate the typical operating pressure range in the
hydraulic systems used in the following applications.
Write a brief report to discuss your findings.
a. controlling wing flaps in airplanes
b. your car’s steering system
c. jacks used to lift cars in a service stationL
Problem 10.2
10.3. An astronaut has a mass of 70 kg. What is the weight
of the astronaut on Earth at sea level? What are the
mass and the weight of the astronaut on the Moon,
and on Mars? What is the ratio of the pressure exerted
by the astronaut’s shoe on Earth to Mars?
10.4. Calculate the attractive force between two students
with masses of 70 kg and 85 kg. The students are
standing about one meter apart. Compare their attrac-
tive force to their weights.
10.5. Basketball player Shaquille O’Neal weighs approxi-
mately 335 lb and wears a size 23 shoe. Estimate the
pressure he exerts on a floor. What pressure would he
exert if his shoe size were 13? State all your assump-
tions, and show how you arrived at a reasonable
solution.
10.6. Investigate the relationship between pressure for the
following situations:
a. when you are standing up barefooted
b. when you are lying on your back
c. when you are sitting on a tall chair with your feet
off the ground and the chair
10.7. Investigate the pressure created on a surface by the fol-
lowing objects:
a. a bulldozer
b. a car
c. a bicycle
d. a pair of cross-country skis62080_10_ch10_p251-302.qxd 5/22/10 12:32 AM Page 293
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