## Lectures in PHYS-107 (14)

Updated: 11 June 2003 Wednesday.

### Week of June 9-13, 2003.

Monday 6/9: DVD: Titanic -- Pressure 2½ miles down. Some reasons the "unsinkable" RMS Titanic sank. Demonstration: 2-liter bottle with holes drilled. 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). Linear Expansion: Most objects expand when heated, shrink when cooled. Length Expansion.

Tuesday 6/10: Length Expansion. Example: 39-foot railroad rail between summer and winter. 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). 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. Q15/16 Take-Home. We've only covered Q15 material, so Q15 is due Thursday 12 June 2003.

Wednesday 6/11: No Class. SPECIAL OFFICE HOURS: Noon to 3pm.

Thursday 6/12: First day to hand in Topic 1 papers.

Friday 6/13: Exam 3 scheduled.

### Week of June 2-6, 2003.

Monday 6/2: Exam 2 re-scheduled.

Tuesday 6/3: Movie clip: 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). Discussion of rotational physics -- Conservation of Angular Momentum, Kepler's Elliptical orbits. Extended Objects: Mass occupies a volume and shape. 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). Mass-to-Volume Ratio (Density). NOTE: Do not confuse the Density of the Materials with the Mass-to-Volume Ratio of the OBJECT. Density of Water built into the SI metric system (1 gram/cm³ = 1000 kg/m³).

Wednesday 6/4: No class.

Thursday 6/5: Pressure = Force / Area. SI unit: Pascal (Pa). Example: Squeezing a thumbtack between thumb and forefinger. 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. Water pressure = 101,300 Pa at depth h = 10.33 m. The mercury barometer and the aneroid barometer. The perils of SCUBA diving. Q13 in-class.

Friday 6/6: Return X2. Go over Exam 2. Curves for both X1 and X2. 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. 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. 1st set of Exam 3 Sample Exams. Example: Air flow around a wing. (Faster air over top means lower pressure on top, so net force is up -- Lift.) Q14 Take-home, due Monday 9 June 2003.

### Week of May 5-9, 2003.

Monday 5/5: Class begins. Distribute syllabus. Introduction to Dr. Phil. Scare students to death. The nature of studying Physics. Science education in the United States. "Speed Limit 70" First equation: Speed = Distance / Time.

Tuesday 5/6: SI Metric System. What do we mean by Measurements? Development of Speed equation for Constant or Average Speed. 60 m.p.h. = "A Mile A Minute". (1848: The Antelope)

Wednesday 5/7: No Class

Thursday 5/8: P-O-R (Press-On-Regardless) example. Rule: You can't average averages. The average speed is the distance remaining / time remaining. A simplified trip to the store -- The S-Shaped Curve. Acceleration. Q1 in-class.

Friday 5/9: Kinematic Equations in 1-D. Equation Without Time. Free-Fall. Kinematic Equations in 2-D. (The guy in the fedora smoking a cigar.) Q2 take-home, due Monday 5/12.

### Week of May 12-16, 2003.

Monday 5/12: Classic Simple Pursuit (Cop and the Speeder). Two kinds of numbers: Scalars (magnitude and units) and Vectors (magnitude, units and direction). Using Vector Addition for Velocities: Upstream, downstream (rivers), Headwind, tailwind, crosswind (airplanes). Q3 in-class. Q2 now due Tuesday 5/13.

Tuesday 5/13: Right Triangles: Sum of the interior angles of any triangle is 180°, Pythagorean Theorem (a² + b² = c²). Trigonometry: SOHCAHTOA Rule. Standard Angle (start at positive x-axis and go counterclockwise). Standard Form: 4.00m @ 30°. Q4 Take-Home.

Wednesday 5/14: No Class

Thursday 5/15:

Friday 5/16: NOTE: Exam 1 scheduled. Moved to Monday 5/19, so you can have the weekend to study.

### Week of May 19-23, 2003.

Monday 5/19: Exam 1

Tuesday 5/20: Uniform Circular Motion (UCM). Space Shuttle in Low-Earth Orbit (There's still gravity up there!). 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.) SI unit of force: Newton (N).

Wednesday 5/21: No Class

Thursday 5/22: Some stories about Sir Isaac Newton. Force is a vector. Free Body Diagrams. Normal Force (Normal = Perpendicular to plane of contact). Sum of forces in x or y equations. Example of 125 kg crate being dragged/pushed around. Variations as we allow for an applied force that it at an angle. 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.). Hand out first sample exam pages for Exam 2. Q7 Take-Home. Topic 2 Worksheet 1 (Blue Sheets) handed out - due last full week of class (6/20).

Friday 5/23: "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. 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. 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. 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. Q7 due. Q8 Take-Home, due Tuesday 5/27.

### Week of May 26-30, 2003.

Monday 5/26: MEMORIAL DAY HOLIDAY - No Class.

Tuesday 5/27: 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. Examples: Minimum radius for safe turns at given speed v. The story of the 50,000 rpm Ultra-Centrifuge and the Fresh Rat's Liver. Artificial Gravity by rotation. Newton's Universal Law of Gravity (or Newton's Law of Universal Gravity). Finding g. (Off by 1/2 %, because Earth is not a uniform, homogeneous sphere.) Tides: High and Low (oceans more or less attracted by Moon), Spring and Neap (Moon and Sun). How Universal Gravity affects Life on Earth (estuaries). Q8 take-home due, but can be turned in later. Q9 take-home, due Thursday 5/29. (Not available online.)

Wednesday 5/28: No Class.

Thursday 5/29: Conservation Laws in Physics. 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. Example: The Yugo and the Cement Truck. Head-on Collisions. What happens in a wreck. How airbags work. Work: A Physics Definition (Work = Force times distance in the same direction). Q10 take-home, due Friday 5/30.

Friday 5/30: Work: A Physics Definition (Work = Force times distance in the same direction). Work = Energy. Kinetic Energy. KE is conserved in Totally Elastic Collisions, but is not conserved in inelastic collisions. Work-Energy Theorem (net Work = Change in K.E.). Potential Energy: Storing energy from applied work for later. Gravitational P.E. = mgh. 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. Example: Roller Coaster (If we neglect air resistance and friction, then 1st hill must be highest. Convert between K.E. [speed] and P.E. [height].) Demo: a suspended bowling ball shows conservation of T.M.E. Exam 2 schedule. Moved to Monday 6/2 so you can have the extra weekend for study. DOUBLE QUIZ Q11-12 take-home, due TUESDAY 3 June 2003.