*Updated: 05 December 2008 Friday.*

Monday 12/1: The Great 19th Century Debate: Is Light a Particle or a Wave? (Wave-Particle Duality did not seem obvious at the time.) The Electromagnetic Wave travels at the speed of light. c = 300,000,000 m/s = 186,000 miles/sec. Electromagnetic Spectrum: Visible light (ROYGBIV=red orange yellow green blue indigo violet). Frequencies HIGHER and wavelengths SHORTER than visible light (UV ultraviolet, X-rays, Gamma rays). Visible light is 400nm to 750nm (4000 angstroms to 7500 angstroms). Cannot "see" atoms with visable light, because the atom is about 1 angstrom across (1.00E-10 meters). The visible light wave is too large to see something that small. So use X-rays. Why Superman's X-ray vision cannot work -- because everyday situations are "dark" in the X-ray band, thankfully! Frequences LOWER and wavelengths LONGER than visible light (IR infrared, Microwave, Radio waves, ELF extremely low frequency). First set of Sample Final Exams. (Click here and here for a copy.)

Tuesday 12/2: Optics: Optics: Geometric Optics (empirical) and Physical Optics (more wave and fieldlike). Ray Tracing: Rays from a spherical source become essentially parallel rays when you are far away. When a straight light ray hits a boundary between one material and another, three things can happen: Reflection, Absorption, Transmission. The Law of Reflection. The Optical Lever -- move a mirror by 10° and the reflected ray moves by 20°. (Dr. Phil's theory on the origin of "seven years of bad luck for breaking a mirror".) When light rays strike a rough surface, you get Scattering, which is reflections off many different angles. People tend to not like photographs of themselves, because they are used to seeing their mirror image -- their normal image, which the rest of us sees, looks "wrong". The Law of Refraction - Snell's Law. Light bent at the interface between two media, because the speed of light changes in the media. (Analogy: If you are driving along the road and your right tires go off onto the soft shoulder, they can't go as fast and the car turns towards the shoulder until all four wheels are driving off the road.) If going from an high index of refraction media to a lower index media ONLY, have a chance for Total Internal Reflection (T.I.R.). This is a "perfect" reflection, better than a mirror. Used in high-end optical systems instead of mirrors. Also useful in fiber optics cables. Quiz 19+20 Double-Quiz is a Take-Home handed out Tuesday 2 December 2008, due Thursday 4 December 2008. (Click here for a copy.)

Wednesday 12/3: Dispersion -- in vacuum all speeds of light are the same,
but in a medium, there are slighltly different n's for each wavelength. As one
goes from a high index of refraction to a low index, increasing the angle of
incidence, white light will start breaking into the rainbox spectrum of colors.
Thin Lenses. Simplest lens surfaces are spherical (convex = bows out, concave =
bows in) and flat (plano). So some lenses might appear to be biconvex,
plano-convex, biconcave, convex-concave. A biconvex lens is also called a
positive or converging lens. Parallel light rays coming into such a lens will
all pass through the focal point, a distance *f* from the center of the
lens. By itself, could use as a magnifying lens. Concentrating sunlight:
burning paper or popping ants? Ray tracing gets same results as doing Snell's
Law on mulitple curved lens surfaces. Handy not to have to do all that
refraction calculations! Real image
formed by passing three rays through a positive thin lens. Three cases: object
distance *p > 2f* (real, inverted, reduced image), *2f < p <
f* (real, inverted, magnified image), *p < f* (virtual, upright,
magnified image = magnifying glass) -- latter two not shown here. Second set of
Sample Final Exams -- the All-Titanic Exam. (Click
here for a copy.) Quiz 21+22 Double-Quiz is
a Take-Home handed out Wednesday 3 December 2008, due Friday 5 December 2008.
(Click here for a copy.)

Thursday 12/4: Return X3. (Click here for a
solution.) Analytic formula for object and
image. Magnification: *M = h' / h = -q / p*. Use of Muliple Lenses --
Focal lengths in series add like series capacitors (by reciprocals) -- one can
adjust the working distance to the object or image, or compact or expand the
physical size of the lens. Dispersion -- in vacuum all speeds of light are the
same, but in a medium, there are slighltly different n's for each wavelength.
Diopters are the reciprocal of focal length in meters. Note that some eyepieces
to optical devices have some diopter built in, so that if you add an eyepiece
to the eyepiece, the second unit may be marked for the *total* diopter,
not the diopter of that particular lens. In multiple lenses the effective
diopter is just the sum of the diopters. A flat piece of glass is 0 diopters.

Friday 12/5: Last Regularly Scheduled Class. Discuss last quizzes and Final Exam. Review course topics in brief and look at a couple of Sample Final Exam Problems. Finish up the day with the course & teacher evaluations for the semester.

Due to time constraints, we obviously have not covered all the material in the text. If you want a rough guide to the topics we didn't cover at the end of the textbook, check out these topics from the PHYS-1150 course.

Monday 9/1: Labor Day <No Classes>

Tuesday 9/2: Class begins. The nature of studying Physics. Science education in the United States. Natural Philosophy. The Circle of Physics.

Wednesday 9/3: Aristotle and the Greek Philosophers. Observation vs. Experiment - Dropping the book and the piece of paper (2 views). Mechanics is the study of motion. So what is motion? Zeno of Elea -- Zeno's Paradoxes. Distribute syllabus.

Thursday 9/4: "Speed Limit 70" First Equation: Speed = Distance /
Time. Development of Speed equation for Constant or Average Speed. delta-x =
x_{f} - x_{i} . Q1 and your PID number. (If you missed class on
this day, check with Dr. Phil sometime soon.)

Friday 9/5: Show Dr. Phil's
WMU Homepage and the PHYS-1070 Class web page.
Development of Speed equation for Constant or Average Speed (con't.). delta-x =
x_{f} - x_{i} , x = x_{0} + v t . A simplified trip to
the store -- The S-Shaped Curve.
Acceleration.

Monday 9/8: Finding the set of Kinematic Equations for constant acceleration. Kinematic Equations for Constant Acceleration. The Equation Without Time -- Avoiding the Quadradic Formula. Finishing The S-Shaped Curve: plotting x-vs-t gives straight line in Region II, but parabolic curves for Regions I and III. Physics Misconceptions: Things you think you know, are sure you know, or just assume to be true in the back of your mind... but aren't true. Aristotle was sure that heavier objects always fell faster than lighter objects, but we did a demostration on Wednesday which showed that wasn't always true. Example: You're driving a car. To speed up, you need to put your foot on the accelerator (gas pedal), so YES, you are accelerating -- True. To drive at a constant speed, you must still have your foot on the accelerator, so YES, you are accelerating -- Not True because constant v means a = 0. To slow down, you must take your foot off the accelerator and put it on the brake pedal, so NO, you are not accelerating -- Not True because v is changing, so a < 0 (negative).

Tuesday 9/9: Speed. 60 m.p.h. = "A Mile A Minute". It's a nice
alliterative phrase and wasn't possible for Man to move at 60 mph until 1848:
The Antelope, but
it really isn't a special speed, just an accident of the English system of
measurement. SI Metric System. What do we mean by Measurements? "Units
will save your life." What is "1 m/s"? We need a few benchmark
values to compare English and SI Metric quantities. *NOTE: English-to-Metric
conversions will NOT, with two exceptions, be tested on in this course. *60
m.p.h. = 26.8 m/s. 1.00 m/s = slow walking speed. 10.0 m/s = World Class sprint
speed (World Record in 100m dash -- 9.69 seconds -- set at Beijing 2008 Summer
Olympics). 345 m/s = Mach 1 (speed of sound). 8000 m/s = Low Earth Orbital
Speed. 11,300 m/s = Earth escape velocity. 300,000,000 m/s = Speed of light.
PTPBIP - Putting The Physics Back Into The Problem. Q2 in-class.

Wednesday 9/10: What do we mean by a = 1 meter/sec² ? You cannot
accelerate at 1 m/s² for very long. Comments on Q2 -- solution already
posted on class webpage. The P-O-R (Press-On-Regardless) road rally problem.
"You can't average averages." Finishing
The S-Shaped Curve: Look at real world
v-vs-t graphs in a car magazine (*Road & Track*, *Car &
Driver*, *Motor Trend*). The line is curved, not straight and has small
hiccoughs (gear shifts). The variable for change in acceleration divided by
change in time is called "jerk" (SI units m/s³), and you can
*feel* it as a jerk.

Thursday 9/11: News: CERN's Large Hadron Collider -- not going to destroy
the Earth. Problem: A car starts at rest, then accelerates at 3.00 m/s²
for 8.00 sec. (a) Find final speed *v*. (b) Find distance traveled
*x*. Assume *x _{0} = 0*. Use 1st kinematic equation to find
(b) -- and check the solution with 4th kinematic equation, The Equation Without
Time. Dr. Phil's Reasonable Significant Figures. Handout on (1) Prefixes for
moving the decimal place for larger and smaller powers of ten in the SI metric
system, (2) Scientific Notation, as in 1.23 × 10

Friday 9/12: Rifle problem con't. Find *t = 0.003333sec*. Again, we can
solve for *t* using two different equations, but will still get the same
result because there is one Physics. Very large acceleration for very short
time. How big is this acceleration? Comparison to Free-Fall: If we ignore air
resistance, all objects near the surface of the Earth fall towards the Earth at
the same rate. *a _{y} = -g* ;

Monday 9/15: Free-Fall: If we ignore air resistance, all objects near the
surface of the Earth fall towards the Earth at the same rate. *a _{y}
= -g* ;

Tuesday 9/16: Motion in Two-Dimensions: You may be able to break it down
into two one-dimensional problems, connected by time, which you can already
solve. Example: The guy with the fedora and the cigar. There are 6 variables
from the first dimension (x_{0}, x, v_{0x}, v_{x},
a_{x}, t), but only 5 from the second (y_{0}, y,
v_{0y}, v_{y}, a_{y}), because time is the same.
Remarkably, with a couple of reasonable assumptions, there are only 3 unknown
variables (v_{0x}, t, v_{y}). Time links the two
one-dimensional problems together. Q4 Take-Home, due Thursday 18 September
2008, in class or by 5pm. *Read the quiz carefully. Part (d) is to look at
how far the ball falls from the turning point in ¼T -- this is that region
near the turning point we discussed for the Michael Jordan "defying
gravity" illusion.*

Wednesday 9/17: Two kinds of numbers: Scalars (magnitude and units) and
Vectors (magnitude, units and direction). Adding and subtracting vectors:
Graphical method. Standard Angle
(start at positive *x*-axis and go counterclockwise). Standard Form: 5.00m
@ 30°. First set of Sample Exam 1's handed out. (Click
here and here for
a copy.)

Thursday 9/18: To generate an analytical method, we first need to look at
some Trigonometry. Right Triangles: Sum of the
interior angles of any triangle is 180°, Pythagorean Theorem (a² +
b² = c²). Standard Angle (start at positive *x*-axis and go
counterclockwise). Standard Form: 5.00m @ 30°. Practical Trigonometry.
S`OH`C`AH`T`OA`. Adding and subtracting vectors:
Analytical method. (Check to make
sure your calculator is set for Degrees mode. Try cos 45° = sin 45° =
0.7071) Why arctangent is a stupid function on your calculator. *For
studying, find vector D = vector A - vector B, where in class you were given
vector A = 5.00 m @ 30° and vector B = 7.00 m @ 120°* . Q5
Take-Home, due Tuesday 23 September 2008, in class or by 5pm.

Friday 9/19: Finding the angle of *vector B* from *tan ^{-1}
(B_{y} / B_{x})*.

Monday 9/22: Two Dangerous Equations. You can only use the Range Equation if the Launch Height = Landing Height. But the sin (2*theta) term in the Range Equation means that (1) 45° gives the maximum range for a given initial velocity and (2) that all other angles have a complementary angle (90° - theta) that gives the same range (but a different time and height). High and low trajectories for Range Equation. Types of Motion studied so far: No motion, Uniform motion (v=constant, a=0), Constant Acceleration. Up next: Uniform Circular Motion (UCM). Second Sample Exam 1. (Click here and here for a copy.)

Tuesday 9/23: Uniform Circular Motion (UCM): speed is constant, but vector
velocity is not; magnitude of the acceleration is constant, but the vector
acceleration is not. Velocity is tangent to circle, Centripetal Acceleration is
perpendicular to velocity and points radial INWARD. a_{c} = v²/r.
Space Shuttle in Low-Earth Orbit. (There's still gravity up there!) Q6
Take-Home, due Thursday 25 September 2008, in class or by 5pm.

Wednesday 9/24: More on U.C.M. Possible to get quite high values for the
centripetal acceleration, a_{c}. F-16 and "9 g" turns. Texas
Motor Speedway and drivers passing out in middle of turns. Hard drive failures.
The guard around a circular saw blade takes the sawdust and broken bits which
shoot out tangentially from the blade and redirects them to a bucket --
improves safety and makes less of a mess. Classic Simple Pursuit (Cop and the
Speeder). Starting from rest, the contant accelerating cop ends up with a final
speed twice that of the uniform motion speeder -- because they both have to
have the same average speed (same place, same time). There are two times when
they are in the same place and the same time -- the other solution is at t=0.

Thursday 9/25: Using Vector Addition for Velocities: Upstream, downstream
(rivers), Headwind, tailwind, crosswind (airplanes). Recap: Our studies so far
have described "How" things move, and allow to say "When"
and "Where" things move, but not "Why" things move. For
that we have to start talking about Forces -- and that means Newton. Some
stories about Sir Isaac Newton. Newton's Three Laws of Motion: Zeroeth Law -
There is such a thing as mass. First Law - An object in motion tends to stay in
motion, or an object at rest tends to stay at rest, unless acted upon by a
__net external force__. Second Law - F=ma. Third Law - For every action,
there is an equal and opposite reaction, __acting on the other body__.
(Forces come in pairs, not apples.) *NOTE: No quiz today -- will hand out
next week.*

Friday 9/26: Demo: Rodney Reindeer and U.C.M. Newton's 3 Laws continued. SI
unit of mass = kilogram (kg). SI unit of force = Newton (N). English unit of
force = pound (lb.). English unit of mass = slug (Divide pounds by 32.). Force
is a vector. Free Body Diagrams. Normal Force (Normal = Perpendicular to plane
of contact). The normal force does NOT automatically point up and it is not
automatically equal to the weight -- we have to solve for the normal force. Sum
of forces in *x* or *y* equations -- either will be equal to 0
(Newton's 1st Law) or *ma* (Newton's 2nd Law). Example of 125 kg crate
being dragged/pushed around.

Monday 9/29: Free Body Diagrams. Normal Force (Normal = Perpendicular to
plane of contact). The normal force does NOT automatically point up and it is
not automatically equal to the weight -- we have to solve for the normal force.
Sum of forces in *x* or *y* equations -- either will be equal to 0
(Newton's 1st Law) or *ma* (Newton's 2nd Law). Example of 125 kg crate
being dragged/pushed around. Variations as we allow for an applied force that
it at an angle. "You can't push on a
rope." Since the force from a wire/string/rope/chain/thread/etc. can
only be in one direction, Dr. Phil prefers to call such forces T for Tensions
rather than F for Forces. Simple pulleys (Massless, frictionless,
dimensionless, only redirect the forces). "There is no free lunch."
The bracket for the pulley will have to support a force greater than the weight
of the hanging object. Mechanical advantage: multiple pulleys allow us to
distribute the net force across multiple cables or the same cable loop around
multiple times. Tension in the cable is reduced, but you have to pull more
cable to move the crate. Discussion of "two pound test fishing line",
stretching and breaking of cables, Safety Factors. Comments on Exam 1.

Tuesday 9/30: Exam 1. Q7 Take-Home, due Thursday 2 October 2008, in class or
by 5pm. *NOTE: For full credit you must include a Free Body Diagram, properly
labeled.*

Wednesday 10/1: "D.O. Wyble's 3 Things
Physics Students Need to Know." Hanging a sign with angled wires --
still the same procedure: Sketch of the problem, Free Body Diagram, Sum of
Forces equations in the x- and y-directions, solve for unknowns. *For the
problem in class, we had a sign with m = 15.0 kg and two tension forces,
T _{1}-vector = 107.7 N @ 150° and T_{2}-vector = 131.9 N @
45°. You can check to make sure these forces cancel in the x-direction and
support the weight of the sign in the y-direction. *Atwood's Machine -- two
masses connected by a single cable via a simple pulley. They share a common
acceleration,

Thursday 10/2: Inclined plane problems: Change the co-ordinate system,
change the rules. In the tilted x'-y'
coordinates, this is a one-dimensional problem, not two-dimensional. Two
kinds of Friction: Static (stationary) and
Kinetic (sliding). For any given contact surface, there are two coefficients of
friction, *µ*, one for static (µ_{s}) and one for
kinetic (µ_{k}). Static is always greater than kinetic. Q8
Take-Home, due Tuesday 7 October 2008, in class or by 5pm.

Friday 10/3: Static & Kinetic Friction continued: Examples using our 125 kg crate sliding on the floor. If object is at rest, need to "test" to see if an applied external force exceeds the maximum static friction force ("breaks the static friction barrier"). Static Friction can vary from zero to its max value in either direction. Rubber on concrete. Tires rolling with friction on good roads -- this is static friction not kinetic friction because the tires aren't sliding on the pavement. If velocity vector and acceleration vector point in the same direction, then the speed is increasing. If they are in the opposite direction, then the speed is decreasing. In either case, for a car the force involved must be in the same direction as the acceleration vector -- this seems to be confusing whereby the static friction force on the tires from the road points forward when you are speeding up. The conflict arises because you might be thinking "friction opposes motion" and not thinking about the motion of the tires versus the motion of the car. If object is at rest, need to "test" to see if an applied external force exceeds the maximum static friction force ("breaks the static friction barrier"). Anti-Lock Brakes and Traction Control. ABS works by monitoring the rotation of all four wheels. If one wheel begins to "lose it" and slip on the road while braking, it will slow its rotation faster than the other tires, so the computer releases the brake on that wheel only until it is rolling without slipping again.

Monday 10/6: More comments on friction and ABS systems in cars. We are not done with Forces, but some problems cannot easily be solved by using forces. Collisions, for example, are very complex if we have to put in all the forces of bending and breaking and mashing things. Need a simpler way of looking at the problem. "Inertia" is a word which isn't used much today, but it is the same as "momentum" -- represents some kind of relentless quality of movement. It takes a force to change the momentum, otherwise it just continues on, i.e., Newton's 1st Law. Linear Momentum ( p = mv ) is a vector quantity. Newton's form of the 2nd Law -- F = change in momentum / change in time instead of F=ma, but really the same thing. Two extremes in collisions: Totally Elastic Collision (perfect rebound, no damage) and Totally Inelastic Collision (stick together, take damage). Linear momentum is conserved in all types of collisions . Totally Inelastic Collisions. Example: The Yugo and the Cement Truck with numbers. Real Head-On collisions.

Tuesday 10/7: Linear momentum is conserved in all types of collisions . Totally Inelastic Collisions. Examples: Head-on Collisions. Rear-end Collisions. (The Non-Collision -- if the car following is going slower, it isn't going to run into the car ahead. PTPBIP.) 2-D Side Impact (vector) collision. What happens in a wreck. How airbags and seatbelts work. Q9 Take-Home, due Thursday 9 October 2008 (or possibly later).

Wednesday 10/8: Real crashes. More on airbags. Interactions of safety systems. The myth of it being better to be "thrown clear from the wreck", Part II. Totally Elastic Collisions -- some brief comments. Why you want inelastics collisions in a wreck. 5 mph versus 3 mph impact bumpers. "Adobe: The Little Car Made of Clay".

Thursday 10/9: What's the opposite of a collision? An explosion. Or recoil. Example: A pitcher on ice skates at rest -- when he hurls a fastball to the right, he goes to the left. Total momentum of the system remains constant (in this case, zero). We've talked about How things move (Kinematic Equations) and Why things move (Forces, momentum). Now we want to talk about the Effort to make things move. Work: A Physics Definition (Work = Force times distance in the same direction). Q10 Take-Home, due Tuesday 14 October 2008.

Friday 10/10: Work = Energy. Kinetic Energy
-- an energy of motion, always positive, scalar, no direction information.
Work-Energy Theorem (net Work = Change in K.E.).
Using the Work-Energy Theorem to find a final speed. Potential Energy: Storing energy from applied work
for later. Gravitational P.E. = mgh. Location of h=0 is arbitrary choice.
Conservation Laws are very important in Physics. Conservation of
Total Mechanical Energy (T.M.E. = K.E. +
P.E.). Lose angle and directional information because energy is a scalar, not a
vector. Demo: a suspended bowling ball shows conservation of T.M.E. All P.E.
when swings up to a stop on either side, all K.E. at bottom of swing. (There
must be non-conservative forces, such as air resistance and friction in the
pivot point on the ceiling -- because the bowling ball never quite gets up as
high as it starts.) Simulate a Totally Elastic Collision (*p* and
*KE* conserved) with the Executive Time Waster. It can't be totally
elastic because it makes a noise, and that took some of the energy. First
Sample Exam 2. (Click here and
here for a copy)

Monday 10/13: (Columbus Day -- no U.S. mail delivery, but classes meet) Continue with Conservation of T.M.E. (P.E. + K.E.) on a roller coaster. Total energy limits maximum height. If speed at top of the first hill is about zero, then this P.E. is all we have. Cannot get higher, but we can change height for speed. Air Resistance. Low speed and high speed air resistance. If allowed to drop from rest, then a real object may not free fall continuously, but may reach a Terminal Velocity (Force of gravity down canceled by Drag force up) and doesn't accelerate any more. Ping-pong balls versus turkeys or pennies.

Tuesday 10/14:
World's
Record Free-Fall. UCM Revisited. Centripetal Force, F_{c} = m
a_{c}. Note that the Centripetal Force is an ANSWER to the sum of
forces equation -- it does not show up in the F.B.D. directly -- something has
to CAUSE the Centripetal Force, such as a tension, normal force or a
combination of forces. No such thing as Centrifugal Force. Only the Centrepital
Force, which points radial inward, just like the centripetal acceleration. You
aren't forced to the outside, you merely move in a straight line unless there
is a force to keep you on the circle. Test tube example. How you could
"get thrown clear of the wreck" in the old days. Although a
loop-the-loop is not a proper UCM problem, we can apply UCM at the top of the
loop and determine the minimum safe speed for going around the loop without
falling off. At the minimum speed, the Normal Force between the wheels and rail
goes to zero (the wheels just "kiss" the track), so the centripetal
force is just equal to the weight, w = mg. The story of the 50,000 rpm
Ultra-Centrifuge and the Fresh Rat's Liver. Q11 Take-Home, due Thursday 16
October 2008. *NOTE: In the version handed out in class, the word
"brick" should be "cherry pie". NOTE:
The speed 8.00 m/s should be, of course, 7.00 m/s.*

Wednesday 10/15: The Ballistic Pendulum -- We can find the speed of a projectile through an Inelastic Collision followed by Conservation of TME. Making "artificial gravity" for long-duration space flight by living in a rotating object. Power = Work / time. Power is rate that work can be done. 1 horsepower = 1 h.p. = the amount of work that one man, one horse and one plow can do in a day. An engine with "more power" can either do the same work in less time, or do more work.

Thursday 10/16: The formula *w = mg* gives us the gravitational force
near the surface of the Earth. Newton had to work out gravity for anywhere,
hence "Universal Gravity." Specifically Newton was working on trying
to solve the problem of the motion of Mars in the night sky. Newton's Universal
Law of Gravity (or Newton's Law of Universal
Gravity). Takes two masses -- there are two forces, according to Newton's
Third Law. Use Universal Gravity to check "g". The value we calculate
is close, 9.83m/s², which turns out to be only off by 0.2%. Why is it off?
Because using Univeral Gravity in this manner makes the assumption that the
entire Earth is uniform and homogenous from the surface to the core -- which it
is not. We would need calculus to integrate over layers to get the observed
value of 9.81m/s². The Shuttle in Low Earth Orbit (Revisited). Four
Fundamental Forces in Nature: Gravity, E & M, Weak Nuclear Force, Strong
Nuclear Force. Second set of Sample Exam 2's handed out. (Click
here and here for a copy.) Q12 Take-Home, due Tuesday 21
October 2008. (Click here for a copy.)

Friday 10/17: **YES! WE HAVE CLASS TODAY!** Newton's Universal Law of
Gravity (or Newton's Law of Universal
Gravity). Tides (high/low, spring/neap). *Though we are calculating
anything with tides, it is interesting to see how Newton's equations for
gravity apply. With this discussion, we close the book on material eligible for
Exam 2.* Discussion of studying for Exam 2 -- Dr. Phil speaks from
experience. We now need to add attributes to our objects more than just mass
and kinematic variables, forces, momentum, energy. Need to start considering
type and shapes. Three Classical States of Matter: Solid, Liquid, Gas.
Combinations: Condensed Matter (covers both Solids and Liquids) and Fluids
(covers both Liquids and Gasses). Two Extreme States of Matter: Plasma
(electrons stripped off, high temperature), Cryogenics (extreme cold, odd
behavior).

Monday 10/20: Review for X2 from some of our Sample Exam 2 problems. Up until now, our objects really haven't had any dimensions. Extended Objects: Mass occupies a volume and shape. Mass-to-Volume Ratio (Density). NOTE: Do not confuse the Density of the Materials with the Mass-to-Volume Ratio of the OBJECT.

Tuesday 10/21: Comments on the FBD for Q12. Mass-to-Volume Ratio (Density). NOTE: Do not confuse the Density of the Materials with the Mass-to-Volume Ratio of the OBJECT. Floating on the Surface: Mass-to-Volume Ratio of the boat < Mass-to-Volume Ratio of the Liquid. Why Boats Float. Example: Front lab table as a 250 kg boat with 4.00 m³ volume. Q13 Take-Home, due Friday 24 October 2008. (Click here for a copy.)

- Announcements! Dr. Timothy Gay, University of Nebraska, is scheduled to give a public lecture, Wednesday, October 22 entitled, "Football Physics," at 7:00 in 1104 Rood Hall.

Wednesday 10/22: Why Boats Float. Example: Front lab table as a 250 kg boat with 4.00 m³ volume. Buoyant Force = Weight of the Boat = Weight of the Water Displaced by the Submerged Part of the Boat. Calulating the amount of the boat submerged, by using the fact that the mass of the boat and the mass of the displaced water are the same. Archimedes and Eureka! (I found it!)

Thursday 10/23: Pressure = Force / Area. SI unit: Pascal (Pa). Example: Squeezing a thumbtack between thumb and forefinger. 1 Pa = 1 N/m², but Pascals are very small, so we get a lot of them. One Atmosphere standard air pressure = 1 atm. = 14.7 psi = 101,300 Pa. Pressure at a depth due to supporting the column of liquid above. Absolute (total) Pressure vs. Gauge Pressure (difference between two readings). Smooth Fluid Flow. Bernoulli's Equation and the Continuity Equation. Water Tower and the Faucet Problem. Why the water tower needs a vent.

Friday 10/24: Pressure at a depth due to supporting the column of liquid above. Water pressure = 1 atm = 101,300 Pa at depth h = 10.33 m = 33.86 feet. How a straw work. Using a column of liquid to make a barometer to measure air pressure. Switch from water to mercury changes h at 1 atm. from 10.33 m to 0.759m. The aneroid barometer. The perils of SCUBA diving. Why you need a qualified SCUBA instructor.

Monday 10/27: Return X1. ~~MOVE EXAM 2 TO THURSDAY 30 October
2008~~. Bernoulli's Equation and the
Continuity Equation. With smooth constant flow, the flow rate (m³/sec)
must remain constant -- hence the Continuity Equation. The faster the fluid
flow, the lower the Pressure. Example: The aspirator -- a vacuum pump with no
moving parts.

Tuesday 10/28: Bernoulli continued. The faster the fluid flow, the lower the Pressure. Example: Air flow around a wing. (Faster air over top means lower pressure on top, so net force is up -- Lift.) Temperature & Heat. Heat = Energy. Two objects in thermal contact, exchange heat energy, Q. If net heat exchange is zero, the two objects are at the same temperature. Temperature Scales: °F, °C and K (Kelvins).

Wednesday 10/29: Temperature Scales: °F, °C and K (Kelvins). Linear Expansion: Most objects expand when heated, shrink when cooled. Use logic to figure out equation for Length Expansion. alpha = coefficient of linear expansion for a material.

Thursday 10/30: Length Expansion. Example: One 39 ft. (12.0m) steel rail
expands 2.88 mm for a 20°C change in temperature, or nearly a centimeter
from the dead of winter to the height of summer, but that's nearly a meter for
a hundred pieces of railroad track -- about ¾-mile. Expansion joints. I-57
in Chicago and the expanding asphault. *Question: Does the material expand
into a hole when heated, or does the hole expand? (Think about what happens to
the disk removed from the hole -- does it expand or contract when heated?) *

Friday 10/31: Volume Expansion of Solids and Liquids. Coefficient of Volume Expansion usually given for liquids; for solids, beta = 3 × alpha. Beta for liquids usually larger than beta for solids. Why you need an overflow tank for your radiator. Why you shouldn't fill your gas tank completely full, especially as the weather changes. Ideal Gas Law (PV/T = constant). Review of some Sample Exam 2 problems.

Monday 11/3: Exam 2.

Tuesday 11/4: Election Day! The Laws of
Thermodynamics. Heat Energy (Q). The Heat
Engine and Three Efficiencies (Actual, Carnot
and 2nd Law). Fuel Economy (miles per gallon) is not an Efficiency. Q14
Take-Home, due __Thursday__ 6 November 2008.

Wednesday 11/5: The Laws of Thermodynamics.
Heat Energy (Q). The Heat Engine and
Three Efficiencies (Actual, Carnot and 2nd
Law). Fuel Economy (miles per gallon) is not an Efficiency. There is no
conspiracy to keep big 100 m.p.g. cars out of our hands. To use less fuel, do
less work. Smaller, lighter cars with smaller, lighter engines. To improve
efficiency, can reduce T_{C} or raise T_{H} .

Thursday 11/6: When a heat engine is cold, T_{C} = T_{H} .
Can't get any useful work done. Reverse the arrows in the Heat Engine and you
get a Refrigerator. Cannot place an open refrigerator or a window air
conditioner in the middle of a room and cool the room, because the exhaust heat
to the hot side includes the heat pulled from the cold side plus the work done
on the compressor. A Heat Pump is a reversible system which cools inside of the
house in summer and heats the inside of the house in winter -- just because it
is cold outside, doesn't mean there is not heat energy Q in the outside air.
(There *has* to be, otherwise the air would be at 0 K.) Waves: Single
Pulse vs. Repeating Waves. The motion of the material vs. the apparent motion
of the wave. For Repeating Waves, we have a
Repeat Length (wavelength) and a Repeat Time (Period). Frequency = 1/Period.
Wave speed = frequency x wavelength. Demonstration: the Slinky shows both
longintudinal (string type) and transverse waves (sound type).

Friday 11/7: Waves and Resonance continued. Standing Waves on a string. Fundamental, First Overtone, Second Overtone, etc. Demonstration: First and higher overtones on a string driven by a saber saw. Standing Waves in a tube. Brass instruments start from the "natural trumpet", which can only play the fundamental and overtones for the pipe. Woodwind instruments get more complicated. Topic 2 Worksheets on taking real world data and analysing it. (Click here for a copy of Worksheet 1.) Q15 Take-Home, due Tuesday 11 November 2008.

Monday 11/10: Tuning forks, resonance boxes. The range of "normal"
human hearing: 20Hz-20,000Hz (10 octaves). Artilleryman's ear -- mid-range
hearing loss. *NOTE: Quiz tomorrow will NOT be In-Class.*

Tuesday 11/11: Veteran's Day (not a WMU holiday). Constructive and Destructive Interference. Acoustics of concert halls. dB = decibel, a logarhythmic scale. NOTE: A regular log scale is based on exponents: 100 = 1, 101 = 10, 102 = 100, etc. So log(1) = 0, log(10) = 1, log (100) = 2, etc. The dB scale is similar, but every 10 dB is a change of about 2, and ever 20 dB is a change of 10. So a 90 dB sound is 20 times louder than a 60 dB sound (90dB - 60 dB = +30dB = 20dB + 10dB or 10 ×2 = 20 times). Q16 Take-Home, due Thursday 13 November 2008. (Click here for a copy.)

Wednesday 11/12: dB = decibel, a logarhythmic scale. See tables in textbook.
Why driving in around in a very quiet car *and* the windows rolled up
tight is A Very Bad Idea. The speed of sound in air: 334 m/s @ 0°C and 344
m/s @ 20°C. Takes time for sound to travel.

NOTE: From Friday 11/7: Topic 2 Worksheets on taking real world data and analysing it. (Click here for a copy of Worksheet 1.)

Thursday 11/13: If you exceed the wave speed in a material, you get a Shock
Wave -- distinctive V-shaped pattern from front and back of moving object.
Sonic booms in air (actually get a double-boom, because of the two V's.), wake
from a boat in water. The speed of sound in air: 334 m/s @ 0°C and 344 m/s
@ 20°C. Takes time for sound to travel. The Realization that Electricity
and Magnetism were part of the same Electromagnetic Force was a great triumph
of 19th century physics. The Two-Fluid Model of Static Electricity (A & B),
to account for the two types of behavior noted. Franklin's One-Fluid Model of
Electricity. First Set of Sample Exam 3's. (Click here for a copy.) *NOTE: Some people reported
problems downloading Q16 -- I checked, it's there, but already said we'd
collect Q16 on Friday.*

Friday 11/14: Two charges: like charges repel, unlike (opposite) charges
attract. Coulomb's Law looks like
Newton's Law of Universal Gravity. Four
Fundamental Forces in Nature: Gravity, E & M, Weak Nuclear Force, Strong
Nuclear Force. The Hydrogen Atom. Gravity loses to
Electric Force by a factor of 200 million dectillion (!!!). Q17 Take-Home,
due ~~Tuesday 18 November 2008~~ changed to Wednesday 19 November
2008 because I didn't get it posted over the weekend.

Monday 11/17: The Hydrogen Atom. Gravity loses to Electric Force by a factor of 200 million dectillion (!!!). Likewise, the two protons in the nucleus of the Helium Atom require the Strong Nuclear Force to overcome the 231 N electric repulsion. Discussion for the future: Isotopes of the same element have different numbers of neutrons. Coulomb of charge is an enormous amount of charge. Two 1.00 C charges separated by 1.00 meters have a force of one-billion Newtons acting on each other. Real Electric Charges. Two charges: like charges repel, unlike (opposite) charges attract. A Nickel coin has a mass of 5 grams, so about 1/10th of a mole. Each Ni atom has 28 protons and 28 electrons. Or +270,000 C of positive charges and -270,000 C of negative charges. Fortunately, the net charge of a typical nickel coin is... zero.

Tuesday 11/18: How does q_{1} know that q_{2} is there? --
"Action at a Distance" -- Gravity and the Electric Force are not
contact forces. The mathematical construct of the Electric Field. E is not an
observable quantity. (Side example: Methods of measuring speed v, do not
directly measure speed v.) Electric Fields, E = k q / r² (E-field from one
point charge) and F_{E} = q E (Electric Force = charge times E-field
the charge is emersed in). Maximum E-field in air, E-max. Electric Potential (Voltage).
Spark gaps. Voltage can be measured, then used
to find strength of E-field. SI units: E-field is (N/C) or (V/m) - both work.
Charges tend to accumulate on long pointy things, which explains why church
steeples get hit by lightning. Or why it's your fingertips which can get
shocked when reaching for the light switch after walking on carpet in the
wintertime.

Wednesday 11/19: Return X2. Charges tend to accumulate on long pointy things, which explains why church steeples get hit by lightning. Or why it's your fingertips which can get shocked when reaching for the light switch after walking on carpet in the wintertme. Conductors (metals) versus non-conductors (insulators). Semi-Conductors sit in the middle. Sometimes they conduct and sometimes they don't. This means they act like a switch or valve, and this is the basis for the entire electronics semi-conductor industry.

Thursday 11/20: D.C. and A.C. circuits. Ohm's Law. V=IR form. (Ohm's "3 Laws"). The Simplest Circuit: Battery, wires, load (resistor). Series and Parallel Resistors. Two devices connected together in a circuit can only be connected two ways: series or parallel. In Series, same current, share voltage. Equivalent resistance is always larger. In Parallel, same voltage, share current. Equivalent resistance is always smaller.

Friday 11/21: Power dissipated by Joule heating in a resistor. P = I V (3 forms of Power equation to with Ohm's "3 Laws"). Resistor Network Reduction. Having reduced the resistor network to a single equivalent resistance, go back and fill in the table for V = I R and then P = I V. Resistor R1 sees the largest current and dissipates the largest amount of energy per second (Power in Watts). This means it is also the most vulnerable. (Story of Voyager 2 radio "repair" call from 4,000,000,000 miles.) Topic 2 Worksheets 2-4. (Click here for a copy.)

Monday 11/24: "Magnetism is just like Electricity, only different." Real Magnets are dipoles (North and South ends, linked). Break a magnet in half, and you either get two new magnets -- or nothing. So far, there is no evidence that there are Magnetic Monopoles (magnetic charges: isolated North or South poles). Rules similar to Electric Charges: Unlike poles attract, like poles repel. Demos: Cow magnets -- powerful cylindrical, rounded end magnets which get dropped into a cow's first stomach, to collect nails, bits of barbed wire, etc. from continuing on to the cow's other stomachs. The horizontal compass needle rotates until its North end points North (or rather to the North Magnetic Pole, which is of course a South pole of the Earth's magnetic core); the vertical compass rotates so that it lines up with the B-field along the surface of the Earth at the point. At the Equator, the vertical magnetic should be parallel to the ground, at the magnetic poles, it should be perpendicular to the ground. Is the Earth's magnetic field going to flip some day? SI Units for B-field: (1 Tesla = 1 T). "Other" unit for B-field: ( 1 Gauss = 1 G ; 1 T = 10,000 G ). Earth's B-field is about 1 Gauss at the Earth's surface. Example of the 4T NMR magnet at Michigan Tech and the 10-foot radius line on the floor and erasing ATM cards within that circle. Review some Sample Exam 3 problems.

Tuesday 11/25: Exam 3.

Wednesday 11/26: <No Class> WMU Closes for Thanksgiving Holiday at Noon. Classes resume as usual on Monday 1 December 2008.

Thursday 11/27: THANKSGIVING -- No Classes --

Friday 11/28: Recovery from THANKSGIVING DINNER -- No Classes -- (grin)