498 Chapter 15 MATLAB
15.4. Using MATLAB, create a table that shows the rela-
tionship between the units of temperature in degrees
Celsius and Fahrenheit in the range of 50 C to
150 C. Use increments of 10C.
15.5. Using MATLAB, create a table that shows the rela-
tionship among units of the height of people in cen-
timeters, inches, and feet in the range of 150 cm to
2 m. Use increments of 5 cm.
15.6. Using MATLAB, create a table that shows the rela-
tionship among the units of mass to describe people’s
mass in kilograms, slugs, and pound mass in the range
of 20 kg to 120 kg. Use increments of 5 kg.
15.7. Using MATLAB, create a table that shows the rela-
tionship among the units of pressure in Pa, psi, and in.
of water in the range of 1000 Pa to 10000 Pa. Use in-
crements of 500 Pa.
15.8. Using MATLAB, create a table that shows the rela-
tionship between the units of pressure in Pa and psi in
the range of 10 kPa to 100 kPa. Use increments of
0.5 kPa.
15.9. Using MATLAB, create a table that shows the rela-
tionship between the units of power in Watts and
horsepower in the range of 100 W to 10000 W. Use
smaller increments of 100 W up to 1000 W, and then
use increments of 1000 W all the way up to 10000 W.
15.10. As we explained in earlier chapters, the air resistance
to the motion of a vehicle is something important that
engineers investigate. The drag force acting on a car is
determined experimentally by placing the car in a wind
tunnel. The air speed inside the tunnel is changed, and
the drag force acting on the car is measured. For a given
car, the experimental data generally is represented by a
single coefficient that is called drag coefficient. It is
defined by the following relationship:where
Cddrag coefficient (unitless)
Fdmeasured drag force (N or lb)
rair density (kg /m
3
or slugs /ft
3
)Vair speed inside the wind tunnel ( m/s or ft /s)
Afrontal area of the car ( m
2
or ft
2
)The frontal areaArepresents the frontal projection
of the car’s area and could be approximated simply
by multiplying 0.85 times the width and the height
of a rectangle that outlines the front of the car. This
is the area that you see when you view the car from
a direction normal to the front grill. The 0.85 factor
is used to adjust for rounded corners, open space
below the bumper, and so on. To give you some idea,
typical drag coefficient values for sports cars are
between 0.27 to 0.38 and for sedans are between 0.34
to 0.5.
The power requirement to overcome air resistance
is computed bywhere
Ppower (W or ft lb/s)
1 horsepower (hp) 550 ft lb/s
and
1 horsepower (hp) 746 W
The purpose of this problem is to see how the power
requirement changes with the car speed and the air
temperature. Determine the power requirement to
overcome the air resistance for a car that has a listed
drag coefficient of 0.4 and width of 74.4 inches and
height of 57.4 inches. Vary the air speed in the range
of 15 m/s V35 m/s, and change the air density
range of 1.11 kg /m
3
r1.29 kg /m
3. The given air
density range corresponds to 0°C to 45°C. You may
use the ideal gas law to relate the density of the air to
its temperature. Present your findings in both kilowatts
and horsepower. Discuss your findings in terms of
power consumption as a function of speed and air
temperature.
15.11. The cantilevered beam shown in the accompanying
figure is used to support a load acting on a balcony.
The deflection of the centerline of the beam is given
by the following equation
where
ydeflection at a givenxlocation ( m)
wdistributed load (N/m)
y
wx
224 EI
1 x
2
4 Lx 6 L
2
2PFdV
Cd
Fd
1
2
rV
2
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