## Lectures in PHYS-107 (17)

Updated: 03 December 2004.

### Week of November 29, 2004.

Monday 11/29: "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. The Electromagnetic Wave travels at the speed of light. c = 300,000,000 m/s = 186,000 miles/sec. Visible Light: ROYGBIV. Electromagnetic Spectrum (ROYGBIV, UV). 3rd Sample Final Exam pages handed out.

Tuesday 11/30: Electromagnetic Spectrum (ELF, Radio, Microwaves, IR, ROYGBIV, UV, X-rays, gamma rays). 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. The Law of Reflection. Q21-22 Double Take-Home Quiz, says its due Thursday 2 December 2004, but you can turn it in on Friday 3 December 2004 by 5pm. (Click here for a copy.)

Wednesday 12/1: The Law of Reflection. Rough surfaces. Corner and Corner Cube reflectors. 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".) The Law of Refraction - Snell's Law. Light bent at the interface between two media, because the speed of light changes in the media. If going from an high index of refraction media to a lower index media, have a chance for Total Internal Reflection (T.I.R.). Thin Lenses. Positive, biconvex, converging lens. Concentrating sunlight: burning paper or popping ants? Real image formed by passing rays through a positive thin lens. Blue Sheets (Topic 2) due today by 5pm (or turn in at beginning of class on Thursday). 4th and 5th Sample Final Exam pages handed out, including the legendary "All-Titanic Final Exam".

Thursday 12/2: 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 (!!!). Likewise, the two protons in the nucleus of the Helium Atom require the Strong Nuclear Force to overcome the 231 N electric repulsion.

Friday 12/3: LAST CLASS. A brief look at Atomic and Nuclear Physics. Handouts: Dr. Phil's Periodic Table. REVIEW. Q23 "The Last Quiz" (Click here for a copy.)

### Week of December 6, 2004.

Thursday 12/9: FINAL EXAM (2:45-4:45pm) 1104 Rood.

## PHYS-107 Fall 2004

### Week of August 31, 2004.

Tuesday 8/31: Class begins. Distribute syllabus. Introduction to Dr. Phil. Scare students to death. The nature of studying Physics. Science education in the United States.

Wednesday 9/1: Physics = Natural Philosophy. "Physics Speak" sounds like English, but words in Physics have exact meanings which must be defined. "The Circle of Physics" or why Physics depends on itself or why the exams are cummulative. The Greek Philosophers. Zeno's Paradox. Aristotle and "heavier objects always fall faster than lighter objects" (except when they don't) -- Demo with textbook and piece of paper.

Thursday 9/2: "Speed Limit 70" First equation: Speed = Distance / Time. Quiz 1 for attendance today.

Friday 9/3: Variations on a theme - more ways to write Speed = Distance / Time (v = d / t, etc.). Topic 1 assigned. (Booklist as HTML; as downloadable PDF file)

### Week of September 6, 2004.

Monday 9/6: LABOR DAY HOLIDAY - No Class.

Tueday 9/7: First Day We'll Require the Textbook... SI Metric System. Why do we need the Metric System? What do we mean by Measurements? Q2 ended up as a take-home, due Wednesday 9/8.

Wednesday 9/8: Significant Figures. What do we mean by v = 1 meter/sec? And World Class sprint speed? Converting m.p.h. to m/s. 60 m.p.h. = "A Mile A Minute".

Thursday 9/9: "A Mile a Minute" (1848: The Antelope) and Chuck Yeager, the X-1 and the Sound Barrier -- Sometimes you have to do the experiment. Q3 in-class.

Friday 9/10: A simplified trip to the store -- The S-Shaped Curve. Acceleration. The Kinematic Equations for Constant Acceleration in 1-D. Common misconceptions: (1) "Speeding up in an acceleration, slowing down is not." NO -- both are accelerations, one positive (speeding up) and one negative (slowing down). Problem creeps up possibly because as drivers, we use one pedal to speed up (the accelerator) and one to slow down (brake). (2) "I am undergoing uniform motion, traveling at constant speed. Therefore I have an acceleration." NO -- if you are traveling at a constant speed, then your "delta-v", the change in the speed, is zero, and therefore you do not have an acceleration. Problem creeps up possibly because as drivers, we know we have to keep our foot on the accelerator to drive at a constant speed on the freeway.

### Week of September 13, 2004.

Monday 9/13: Kinematic Equations for Constant Acceleration in 1-D. What do we mean by a = 1 meter/sec² ? You cannot accelerate at 1 m/s² for very long. Types of Motion: No Motion (v=0, a=0), Uniform Motion (v=constant, a=0), Constant Acceleration (a=constant). We generally cannot accelerate for very long. Example: NASA Genesis satellite crashed last week, going 200 mph (89.4 m/s), stops in two feet (0.610 m), use equation without time to find a = -6551 m/s². How large is this? Free-Fall. All objects near the surface of the Earth, in the absence of air resistance, fall and accelerate at the same rate, g = 9.81 m/s². Equation Without Time -- Avoiding the Quadradic Formula. Q4 take-home, due Tuesday 14 September 2004.

Tuesday 9/14: Two examples of using Kinematic Equations in 1-D. (1) Car accelerating from rest (v0 = 0). (2) Bullet accelerating from rest in rifle barrel. Problem Solving Stategies: List of variables. Count your unknowns. Check your units! So far we are doing motion in just one dimension. But that one direction can be vertical instead of horizontal. Kinematic Equations in 2-D. If x and y are perpendicular axes, then can solve as two 1-D problems connected only by time t. (Start problem with: The guy in the fedora smoking a cigar.) Q4 take-home due today.

Wednesday 9/15: Free-Fall. Falling Down and Falling Up. The Turning Point ( v=0 but a = -g during whole flight). The illusion of "hanging up there in the air" at the turning point. Kinematic Equations in 2-D. Solving two equations in two directions together. (The guy in the fedora smoking a cigar. The body at the base of the building. Is it an "accident"?).

Thursday 9/16: P-O-R (Press-On-Regardless) example. Rule: You can't average averages. The average speed is the distance remaining / time remaining. Classic Simple Pursuit (Cop and the Speeder). Problem with answer: Yes, the Cop and the Speeder are in the Same Place at the Same Time, but the Cop is going twice as fast as the Speeder (they have the SAME average speed). Simple Classic Pursuit versus a more realistic pursuit -- v vs. t graph more like "A Trip to the Store." Solving equations for two different vehicles together. Q5 in-class. Hand out first Sample Exam pages for Exam 1.

Friday 9/17: Q5 Solution. When a object is tossed up with some initial v0y, it will come to rest at the turning point. But when it falls back down to its original height, then vy = -v0y. What about the OTHER solution to the Simple Pursuit problem? We took our algebraic equation from setting x1 = x2, where the two vehicles will be in the same place at the same time, and divide that equation by t. Anytime you can do that, this is equivalent to finding a solution t=0. Any equation with a t² in it must have TWO solutions. Ballistics: vx = constant, ay = -g. If launched horizontally, an object will fall to level ground in the same time as if it is just dropped from rest.

### Week of September 20, 2004.

Monday 9/20: Two kinds of numbers: Scalars (magnitude and units) and Vectors (magnitude, units and direction). Compass points. Standard Angle (start at positive x-axis and go counterclockwise). Standard Form: 5.00m @ 30°. Right Triangles: Sum of the interior angles of any triangle is 180°, Pythagorean Theorem (a² + b² = c²). Trigonometry: SOHCAHTOA Rule. Q6 take-home, due Tuesday 21 September 2004.

Tuesday 9/21: Adding vectors by 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. Adding two vectors by adding x-components, y-components, then finding magnitude and standard angle of the resultant vector. Finding the final vector velocity of The guy with the fedora and the cigar problem. Hand out 2nd set of Sample Exam 1's.

Wednesday 9/22: Physics Help Room. Using Vector Addition for Velocities: Upstream, downstream (rivers), Headwind, tailwind, crosswind (airplanes). Hand out 3rd set of Sample Exam 1's. "Two Dangerous Equations" handout.

Thursday 9/23: 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. Q7 take-home, now due Friday 24 September 2004 AT THE START OF CLASS.

Friday 9/24: Q7 take-home due at start of class. Return Q2, Q3. Q6 and Q7 solutions. Exam 1 review.

### Week of September 27, 2004.

Monday 9/27: Exam 1.

Tuesday 9/28: Types of Motion studied so far: No motion, Uniform motion (v=constant, a=0), Constant Acceleration. 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. Space Shuttle in Low-Earth Orbit. (There's still gravity up there!). Some useful geometry info: Circles (C = 2(pi)r ; A = (pi) r²).

Wednesday 9/29: Similar to comments made about x- & y-motion together, an object in UCM can be thought of as having a tangential motion and a radial inward motion. A demonstration on where the equation for centripetal acceleration (a-sub-c = v²/r) comes from. Our study of Motion in Chapter One really has been in describing and calculating How Things Move. In Chapter Two, we turn out attention to Why Things Move. 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.

Thursday 9/30: 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.) SI unit of force: Newton (N). Some stories about Sir Isaac Newton. Q8 Take-Home, due Friday 1 October 2004 by 5pm.

Friday 10/1: Free Body Diagrams. Normal Force (Normal = Perpendicular to plane of contact). Sum of forces in x or y equations. Pushing a 125 kg crate around. (Near the surface of the Earth, you can use the relationship that 1 kg of mass corresponds [not "equals"] to 2.2 lbs. of weight. So multiple 125 by 2 and add 10%... 250 + 25 = 275... so a 125 kg crate has a weight of mg = 1226 N or 275 lbs.). 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.). Variations as we allow for an applied force that is at an angle.

### Week of October 4, 2004.

Monday 10/4: "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. Elevator Problems. The Normal Force represents the "apparent weight" of the person in the elevator. For the elevator at rest or moving at constant speed, the Normal Force = weight, and the tension of the cable = weight of loaded elevator. But if there is an acceleration vector pointing up, the apparent weight and the tension of the cable increase; if the vector points down, the apparent weight and the cable tension decrease. In true Free Fall, without any air resistance, the Normal Force = 0 and you are floating. Q8 postponed until tomorrow, still on Newton's 1st and 2nd laws.

Tuesday 10/5: 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 and one for kinetic. Static is always greater than kinetic. Static & Kinetic Friction. 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. Q9 now a Take-Home, due in class or by 5pm on Wednesday 6 October 2004.

Wednesday 10/6: Using Static & Kinetic Friction. 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.

Thursday 10/7: Resistive Forces: Friction and 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. World's Record Free-Fall. UCM Revisited. Centripetal Force. No such thing as Centrifugal Force. Only the Centrepital Force, which points radial inward, just like the centripetal acceleration. Q10 now a Take-Home, due on Friday 8 October 2004, but will accept on Monday.

Friday 10/8: UCM Revisited. Centripetal Force. No such thing as Centrifugal Force. The story of the 50,000 rpm Ultra-Centrifuge and the Fresh Rat's Liver. Making "artificial gravity" for long-duration space flight by living in a rotating object. 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. Finding g. (Off by 1/2 %, because Earth is not a uniform, homogeneous sphere.) Revisit the Space Shuttle in orbit problem. Find g at r=6,770,000 meters in class. Going backwards through the problem and find v (the speed of the Shuttle in orbit) and T (the period or time to make one orbit). Originally has estimated T = 90 minutes = 5400 seconds. Actually, using correct g for Low Earth Orbit, we get T = 5542 seconds, or off by two minutes and 22 seconds. For circular orbits, each r has its own g, v and T -- higher orbits see weaker gravity, travel slower and take more time. Low Earth Orbit is 90 minutes, the Moon around the Earth is about four weeks. In between, a geosynchronous orbit has a period T = 24 hours. Place a satellite in such an orbit over the Equator, and the satellite will be to our South and appear not to move in the sky. That's why TV satellite dishes can be aimed once at HBO and then don't have to move.

### Week of October 11, 2004.

Monday 10/11: Return X1. Go over. Announce that Exam 2 will be delayed one week to Monday 25 October 2004, to give you more study time. Hand-out 2nd set of Sample Exam 2's.

Tuesday 10/12: Linear Momentum ( p = mv ) is a vector quantity. 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. 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.)

Wednesday 10/13: Collisions (con't.). Rear-end Collisions. What happens in a wreck. How airbags work. Note: We do NOT want our cars to have Totally Elastic Collisions -- the whiplash on our fragile bodies would be awful. Instead, our cars are designed to crumple and "die" for us. Tomorrow: Work and Energy -- "Work" in Physics isn't what you think it is.

Thursday 10/14: 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). Newton's form of the 2nd Law. Work: A Physics Definition (Work = Force times distance in the same direction). Work = Energy. Kinetic Energy -- an energy of motion, always positive, scalar, no direction information. Work-Energy Theorem (net Work = Change in K.E.). Hand back Q4 and Q9. Q11 Take-Home, due Monday 18 October 2004.

Friday 10/15: Work and Energy continued. 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.)

### Week of October 18, 2004.

Monday 10/18: Exam 2 is NOT today, but next week, Monday 25 October 2004. Continue with Conservation of T.M.E. (P.E. + K.E.) on a roller coaster. Total energy limits maximum height. 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. Q11 take-home was due today. Q12 on K.E. and P.E. in-class.

Tuesday 10/19: Demo: The loop-the-loop track and a steel ball. Demo: The Ballistic Pendulum -- We can find the speed of a projectile through an Inelastic Collision followed by Conservation of TME. Demo: The "Rolling Uphill" toy. The cylinder rolls down the slope, its P.E. converting to K.E. The double cone-shape seems to roll "up the hill", but actually its center is also falling as the track gets wider, so its P.E. is changing to K.E., too. 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.

Wednesday 10/20: 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). 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. Pressure = Force / Area. SI unit: Pascal (Pa). Example: Squeezing a thumbtack between thumb and forefinger.

Thursday 10/21: SI unit of pressure is the Pascal. 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). Pressure due to a column of water = 1 atm. at h = 10.33m = 33.86 feet. The perils of SCUBA diving. "Physics Does Not Suck" (See D.O. Wyble's 3 Rules for Physics Students) - To draw water up a straw, one decreases the air pressure in your mouth by geometry and the outside air pressure PUSHES the water up the straw. Q13 Take-Home due Friday 22 October 2004 by 5pm. Q13 NOTE: I neglected to give you a mass for the empty box --- let's use m = 0.200 kg.

Friday 10/22: Air pressure holding up a column of liquid in a sealed tube makes a barometer. Unfortunately, if you use water, then if P = 1 atm, then h = 10.33m. However, if you switch from water to mercury (density of Hg = 13,600 kg/m³ or 13.6 times that of water), then h = 10.33m ÷ 13.6 = 0.760 m or just under 30". This I can mount on a wall and see both top and bottom. I can carry this around. Often meteorologists in the U.S. give air pressure (barometric pressure) in mm of Hg or inches of Hg. Weather changes can be noted by the air pressure and whether it is rising, falling or stationary. Mercury barometers aren't used much anymore for safety reasons. Aneroid barometer. Exam 2 review.

### Week of October 25, 2004.

Monday 10/25: Exam 2.

Tuesday 10/26: Video Demo Day. DVD clips: (1) Speed (You have to have some positive v0y if you want to jump a gap -- even with a bus.) (2) 2001: A Space Odyssey (What would it look like to have use centripetal force for artificial gravity? Stanley Kubrick's 1968 movie showed us a large rotating space station and a smaller rotating carousel on a ship to Jupiter.) Video Clip: Skylab missions (motion in free fall).

Wednesday 10/27: 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. Buoyant Force = Weight of the Boat = Weight of the Water Displaced by the Submerged Part of the Boat.

Thursday 10/28: Archimedes and Eureka! (I found it!) Smooth Fluid Flow. Bernoulli's Equation and the Continuity Equation. Water Tower and the Faucet Problem. Why the water tower needs a vent. Q14 Take-Home, due Monday 1 November 2004 by 5pm.

Friday 10/29: DVD: Titanic -- Pressure 2½ miles down. Some reasons the "unsinkable" RMS Titanic sank.

### Week of November 1, 2004.

Monday 11/1: Return X2. First posted results from The Predictor. Last day to Drop. Demo: 2 liter bottle with holes drilled in it. Water streams out, falling in a parabolic arc -- only if the cap is left off. Close the cap and the water stops (why?). To Glug or Not to Glug. With water on the front table, plus the piles of Exam 2's, decide to have everyone turn in the current Take-Home quiz on Tuesday.

Tuesday 11/2: Bernoulli continued. Finish the water tower problem. Example: Air flow around a wing. (Faster air over top means lower pressure on top, so net force is up -- Lift.) Example: The Physics of why the shower curtains wants to cling to your leg.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 11/3: Linear Expansion: Most objects expand when heated, shrink when cooled. Length Expansion. Example: One 39 ft. (12.0m) steel rail expands 5.88 mm from winter to summer, but that's 0.75 meters for every mile of railroad track.

Thursday 11/4: 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? Volume Expansion of Solids and Liquids. Ideal Gas Law (PV/T = constant). Q15 Take-Home, due Monday 8 November 2004.

Friday 11/5: Microscopic theory of temperature -- vibration and motion of atoms and molecules (P.E. + K.E.). The Laws of Thermodynamics. Heat Energy (Q). The Heat Engine and Three Efficiencies (Actual, Carnot and 2nd Law).

### Week of November 8, 2004.

Monday 11/8: 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. The Laws of Thermodynamics and the U.S. Patent Office -- Why perpetual motion machines cannot exist, whether they can deliver useful work or not. (There's no such thing as a free lunch. But then you knew that, didn't you?)

Tuesday 11/9: Heat Energy (Q) and Temperature Change & Phase Change. Water has a high Latent Heat of Vaporization: (1) Long boiling time, (2) Firemen use it to take heat energy out of the fire zone.

Wednesday 11/10: 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). Standing Waves on a string. Fundamental, First Overtone, Second Overtone, etc. Demonstration: First and higher overtones on a string driven by a saber saw.

Thursday 11/11: The Blue Sheets (Topic 2) -- Collecting your data. Waves and Resonance continued. Standing Waves in a tube. The range of "normal" human hearing: 20Hz-20,000Hz (10 octaves). Tuning forks, resonance tubes. Beat frequency. Constructive and Destructive Interference. Some accoustical considerations of our Lecture Halls (1110 and 1104 Rood), basketball arenas for rock concerts and Carnegie Hall in New York City. Today's quiz, Q16, ended up a take-home due Friday 12 November 2004 by 5pm. Then we have a Double-Take-Home Quiz, Q17-18, due Monday 15 November 2004. (Click here for a copy.)

Friday 11/12: VHS Video: Tacoma Narrows Bridge Disaster (1940). Why the Mackinac Bridge can't do a Tacoma Narrows. Exam 3 review. REMINDER: Monday 15 November 2004 is (1) date of Exam 3 and (2) last day to turn in a Draft Paper for quick evaluation (this is not required).

### Week of November 15, 2004.

Monday 11/15: Exam 3.

Tuesday 11/16: Artilleryman's ear -- mid-range hearing loss. dB = decibel, a logarhythmic scale. The speed of sound in air. Sonic Booms and other shockwaves. Bullwhip stories. The first silencers were for rifles, so you could hunt in town without disturbing people. Story of tiny sonic booms from bullets reflected by telephone poles... early 1900s.

Wednesday 11/17: The Realization that Electricity and Magnetism were part of the same Electromagnetic Force was a great triumph of 19th century physics. Franklin's One-Fluid Model of Electricity. Real Electric Charges. 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.

Thursday 11/18: Gravitational, Electric and Magnetic Forces are not Contact Forces - Require Fields. Electric Fields. 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. D.C. and A.C. circuits. Ohm's Law. The Simplest Circuit: Battery, wires, load (resistor). First day Topic 1 Book Reports are due. (Continues through Monday 22 November 2004.) Q19 Take-Home, due Monday 22 November 2004.

Friday 11/19: Dr. Phil off having a colonoscopy -- Bill Semrau pinchhitting -- demos of Series and Parallel connections. Hand out first Sample Final Exam.

### Week of November 22, 2004.

Monday 11/22: Series and Parallel Resistors. Discussion of Significant Figures again. 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. 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 radio "repair" call from 4,000,000,000 miles.) Last day to turn in Topic 1 Book Reports. Second Sample Final Exam. (Available on class home page as PDF download, too.)

Tuesday 11/23: Return X3. Hand out X3 Solution. Hand out Topic 2 Worksheets to go with Blue Sheet data sheet. (Available on class home page as PDF download, too.) Real batteries consist of a "perfect" battery (Electromotive force = emf) in series with a small internal resistance, r. As chemical reaction in battery runs down, the internal resistance increases. Tip for weak car battery on cold day: Run headlights for 30 to 90 seconds. High internal resistance will warm the battery and make it more efficient. Proper procedure for jump starting a car. (And why doing it wrong ranges from dangerous to deadly.) Q20 in-class quiz on series and parallel resistors.

Wednesday 11/24: WMU Classes end at NOON -- so the Noon section of PHYS-107 is cancelled.

Thursday 11/25: THANKSGIVING DAY HOLIDAY - No Class.

Friday 11/26: No class.