Chapter 18
E18.1 (a) Explain briefly why databases for initial process selection need to be subdivided into
generic process classes, while material selection can be conducted on a single database for all
materials.
(b) After initial screening of unsuitabl

(b) 2.5 Si-Fe soft magnetic alloy has H c = 27.8 A/m and e = 40 ohm.cm.
The question: what is the frequency of the transformer? If it is a low frequency transformer the .5 SiFe alloy is the best choice (it is cheap). If the frequency is above 100 kHz it w

263
Now, since the disk rolls without slip along a xed surface, we have that
F
vP = 0
(5.620)
Then, from kinematics of rigid bodies, the velocity of point O is given as
F
vO = F vP + F R (rO rP )
(5.621)
where R is the reference frame of the disk. Now, si

266
Chapter 5. Kinetics of Rigid Bodies
Therefore, Eq. (5.637) reduces to
MP =
F
d
dt
F
HP
(5.645)
Examining the free body diagram in Fig. 5-24), we see that the forces R and N
pass through point P . Consequently, the moment relative to point P is given a

265
Furthermore, the spring is unstretched when = 0 which implies that L = 0.
Therefore, we obtain the spring force as
Fs = 2Kr Ex
(5.634)
Finally, the damping force is given as
Fd = c
F
vA
3
Fv
A
Fv
A
(5.635)
Using F vA from Eq. (5.626), we obtain Fd as

262
Chapter 5. Kinetics of Rigid Bodies
Question 520
A uniform circular disk of mass m and radius r rolls without slip along a plane
inclined at a constant angle with horizontal as shown in Fig. P5-20. Attached
to the disk at the point A (where A lies in

264
Chapter 5. Kinetics of Rigid Bodies
Fs
Fd
mg
R
N
Figure 5-24
Free Body Diagram for Question 6.11
Ex
Ey
Figure 5-25
6.11
uv
Downward Direction uV in Terms of Basis cfw_Ex , Ey for Question
where uv is the unit vector in the vertically downward directi

261
Now the total energy in reference frame F is given as
F
E = FT + FU
(5.610)
First, the kinetic energy of the disk in reference frame F is given as
F
T =
1F
1 F
m v Fv +
H F D
2
2
(5.611)
Using the expression for F v from Eq. (5.561), we have that
1 F

260
Chapter 5. Kinetics of Rigid Bodies
Method 2: Eulers 2nd Law Relative to Instantaneous Point of Contact
Since the point of contact is an arbitrary point, we have that
F
MP ( rP ) m aP =
r
F
d
dt
F
HP
(5.601)
First, the angular momentum relative to poi

259
Applying Eulers 2nd law relative to the center of mass of the disk, we have
that
F
d F
H
(5.589)
M=
dt
Now we have that
F
ID
(5.590)
H = F D
Now since cfw_er , e , ez is a principle-axis basis, we have that
D = Ir r er er + I e e + Izz ez ez
I
Then,

Chapter 16
E16.1. Define refractive index. Give examples of devices that make use of refraction.
Answer. When light enters a material from air or vacuum, it slows down. The index of refraction, n
is the ratio of its velocity in vacuum, c o , to that in th

Answer.
75Ni-5Cu-2Cr-Fe Soft Magnetic
Alloy, "Alloy 3", soft (annealed)
79Ni-4Mo-Fe Soft Magnetic Alloy,
"Alloy 4", soft (annealed)
E15.16. A magnetic material is required for the read/write head of a VCR. It must have high hardness
to resist wear and the

E15.17 Make a chart with Atomic number on the x-axis and Magneton moment per atom (Bohr
magneton) on the y-axis (use linear scales) to identify the ferromagnetic elements. How many are
there? Which have the highest magneton moment per atom?
Answer. Nine e

Answer.
Epoxies
PTFE
Phenolics
Polyetheretherketone (PEEK)
Silicone elastomers
E17.16. A vat is required to hold hot caustic soda, NaOH, a strong alkali. Use the Select facility in
CES to find metals that resist strong alkalis very well.
Answer. Copper
Ni

might suspect that the two were, in some way, related. Make a graph with Standard reduction potential
on the x-axis and Work function on the y-axis to find out if they are. What is your conclusion?
Answer. The plot shows that there is a correlation betwee

E17.9. The waste stream of a fertilizer plant includes dilute sulfuric acid. The dilute acid is stored in
surface tanks some distance from the plant. It is suggested that the ducting to carry the acid to the
tanks could, most economically, be made of wood

The electrons accumulate on the iron giving it a negative charge that grows until the electrostatic
attraction starts to pull the Fe+ ions back onto the metal surface, stifling further dissociation. At this
point the iron has a potential (relative to a st

Polystyrene (PS)
Soda-lime glass
Exploring the science with CES Elements
E16.15. The Hagen-Rubens law an empircal law says that the reflectivity of metals, R , is given by
R 1 0.02 e
where the electrical resistivity e is in .cm. Make a chart with R on the

Ceramics
Glass
Titanium would appear to be the best, though expensive, choice: its inherent resistance to attack by
HCl is high, and inhibitors exist that give added protection. The alternative, suggested by the table, is
ordinary steel pipe work that is

Aluminum alloys
Acrylonitrile butadiene styrene (ABS)
Polystyrene (PS)
Granite
Non age-hardening wrought Al-alloys
E16.12. You are asked to suggest the best choice of cheap polymer for a new line of injection molded
costume jewelry. Its transparency must

17.10 Exercises
E17.1. By what mechanisms do metals oxidize? What determines the rate of oxidation?
Answer. When is exposed to air a thin surface film of oxide forms, following the oxidation reaction
M ( metal ) + O( oxygen ) = MO( oxide ) + energy
causin

the surfaces, neutralizing the charge. If the temperature of the sample is constant, then so is Ps and no
current flows through a circuit linking the faces of the disk. An increase in temperature, however,
causes expansion and that changes the net dipole

E16.4. Why are metals good reflectors of radiation?
Answer. Metals have an enormous number of very closely spaced levels in their conduction band;
the electrons in the metal only fill part of this number. A photon with energy h can excite an
electron only

258
Chapter 5. Kinetics of Rigid Bodies
Using Fig. 5-23, it is seen that the following forces act on the disk
N
= Reaction Force of Track on Disk
FR
= Rolling Force of Track on Disk
mg = Force of Gravity
Now from the geometry we have that
N = Ner
FR
(5.57

254
Chapter 5. Kinetics of Rigid Bodies
Question 517
A uniform disk of mass m and radius r rolls without slip along the inside of
a xed circular track of radius R as shown in Fig. P5-17. The angles and
measure the position of the center of the disk and t

243
Eq. (5.467) simplies to
N sin + P cos =
ml
6
(5.468)
Determination of System of Two Dierential Equations of Motion
The rst dierential equation of motion is obtained directly from Eq. (5.458),
i.e.,
ml 2
ml
cos
sin = P
(5.469)
mx +
2
2
The second di

B. N. Popov
ECHE 571/Fall 2009
Quiz 3
Basics of Corrosion Measurements
1.
(a) Define mixed potential theory.
1
25 points
(b) Explain how one estimates the polarization resistance
experimentally.
25 points
2
(c) Which values should be given to calculate th

B. N. Popov
ECHE 571/Fall 2009
Quiz4
Passivity
1.
(a) Define the Standard Fade potential
5 points
Read Ch 5 Passivity (Uhlig )
(b) Plot schematically the polarization curve for the active/passive
metal
5 points
(c) Define the critical passivation current