Why Should I Care? Teaching Physics to Non-Believers Robert E. Thorne Cornell University Physics 207 at Cornell Content: Calculus-based course on mechanics and heat (1st course of 2 semester sequence) Format: 3 - 1 hour lectures

2 - 1 hour recitations 1 - 2 hour lab each week Enrollment: 300 Syllabus Describing motion along a line: x, v, a relations Motion in a plane; projectile motion Newton's laws and forces; free-body diagrams Circular motion; friction and fluid drag

Energy; kinetic energy, potential energy; power Oscillations: free, driven, damped Momentum and impulse; collisions; center of mass Torques and static equilibrium; elasticity Heat; thermal expansion; heat capacity; heat transport Static fluids: pressure, buoyancy, surface tension Moving fluids: continuity, Bernoulli, viscous drag and flow Traveling and standing waves Physics 207 Clientele Major: Biological and life sciences, chemistry, geology, human

ecology, meteorology, english, government, economics, . . . pre-med/pre-vet Academic year: Freshman: 3% Sophomore: 55% Junior: 37% Senior: 5%

What do you plan to do after graduating from Cornell? (Select all that apply.) Med school 61% Grad school in the sciences 32% Get a job

18% Vet school 5% Other grad school 5% Law school

4% Other professional school 4% Serve in the military 2% What was your primary reason for signing up for Physics 207?

To fulfill a requirement: 96% Interested in physics: 3% Course had great reputation: 1%

What was your attitude towards Physics 207 when you signed up for it? (Select all that apply.) Sheer terror 18% Anxious 44%

Afraid it will kill my chance of getting into professional/graduate school 20% Comfortable: a good chance to develop some useful skills 26% Overall Course Evaluation Score (out of 5)

5 4.5 Physics 116 ( Majors) 4 Physics 112 (Engineers) 3.5 3

Physics 207 (Pre-Meds et al.) 2.5 2 1999 1998 1997 1996

1995 1994 1993 1992 1991 1990

Year What adjectives would you use to describe Cornell Pre-Meds? What adjectives would you use to describe Cornell Pre-Meds? Brilliant Driven Ruthless Hypercompetitive Insecure

What adjectives would you use to describe Cornell Physics Faculty? What adjectives would you use to describe Cornell Physics Faculty? Brilliant Driven Ruthless Hypercompetitive Insecure

Physics 207 Clientele > 50% female, ~15% under-represented minority significant socioeconomic diversity How can we achieve more diversity in physics if we cant reach these non-believers? Guiding Principles: These students are smart, curious and motivated. Physics is fascinating and empowering.

If students dont learn the material and dont like the course . . . its our fault!!! Guiding Principles: Students in physics courses only master a small fraction of the material with which they are presented. Focus on fundamental concepts and keep the math simple. Leave out tricky details, esoterica, and advanced math. Guiding Principles:

Physics provides the foundation for analyzing data and solving problems across the sciences and engineering. Emphasize transferable skills and their relevance to future careers: plotting data, sketching functions, dimensional analysis, proportional reasoning, orders of magnitude, approximate models, estimation, exponentials, power-laws . . Guiding Principles: Life science/premed students see very little math in their other science courses.

The math that trips them up is not calculus, but high-school level math. How much use of the following pre-calculus mathematics skills have you made in your previous science (NOT MATH) courses at Cornell? Trigonometry (triangles, sines and cosines in relations between sides)? none a little some

a lot 33% 29% 28% 11% Pi what squared? Long John, you should be able to get this. Proportional reasoning (if I double x, what happens to y?) ?

none 12% a little 34% some 38% a lot 16% Sinusoidal functions of time or position, e.g., x(t) = A cos (t + ) none 63% a little 22%

some 12% a lot 4% Order of magnitude estimates / "back of the envelope" calculations? none 31% a little 32% some 31% a lot 7%

Zeros, limits and asymptotes of simple functions? none 37% a little 31% some 22% a lot 8% Semi-log plots, i.e., graphs of log(y) versus x, or y versus log(x)?

none a little some a lot 37% 35% 24% 5% Log-log plots, i.e., plots of log(y) versus log(x); use to extract power law exponent b in y = A xb?

none 51% a little 30% some 15% a lot 4% Guiding Principles: Life science/premed students see very little math in their other science courses.

Provide pre- and early-course tutorial support in elementary scientific mathematics so that they can focus on learning physics, not math. Student comments from course evaluations in Physics 207: Student comments from course evaluations in Physics 207:

"I hate physics!" Student comments from course evaluations in Physics 207: "I hate physics!" "Physics makes me feel dumb! Guiding Principles: Most students don't hate physics. They hate how physics makes them feel

about themselves. There are, of course, other ways in which schools represent a psychic fall; and teachers, the guardian angels of its trajectory. Although schools in a democracy purport to exist for the creation of a level playing field, it does not take us long to discover that level playing fields exist mainly to sort out winners from losers. Unless we came from a large family with parents who went out of their way to play favorites, school was our first introduction to the idea of relative merit. . . But that oppressive sense of minute gradation, of success not

as a mansion of many rooms but as a ladder of infinite rungs where does that exist but in a classroom, or in the imagination of the adult who still sits there? Taking your degree is the most precise phrase in all of education: that is what we take from our first day of kindergarten, our degree of relative worth. The educational apple of Adams Fall . . . did not give us the knowledge of good and evil but of good, better and best, world without end. From Why We Hate Teachers by Garret Keizer, published in Harpers, September 2001. Provide emotional support and encouragement to struggling students. Youre not dumb! This stuff is challenging. Be patient with yourself.

Send out regular supportive emails. Eliminate tricks, surprises, and needlessly punitive practices. Maintain an even, predictable flow. Use a pragmatic, non-inflammatory grading system. Exam questions: straightforward variants of homework and lab problems; high score of 100 ok. Absolute grading, i.e., no curve. 85-100% = A, 70-85% = B, 55-70% = C.

Dont set median to a C+! Who said we need to be the weed-out course? Dont rub their noses in the fact that they cant master everything in one semester. Guiding Principles: Every grade of D or F we award represents a failure on our part. Wastes student time and university resources; creates bad PR; and lowers the median. Intervene early and often.

Get non-performers out of the course and into remedial courses. Guiding Principles: Get students involved! Ask multiple choice questions during lecture that illustrate important concepts. Involve them in lecture demonstrations. Quiz them while they are doing lab experiments. Use regular on-line surveys.

Student comments from course evaluations in Physics 207: Why I am forced to take this course?" What use is this stuff to my major? Many students are driven by a desire to do something useful or lucrative, not by truth and beauty. Many have little idea of why or how physics may be relevant to their future careers.

Many students continue to view physics as irrelevant even after taking high school and college physics courses. Illustrate physics with applications from many disciplines, to emphasize the interconnectedness of science, to show how phenomena and theory in distinct areas are interleaved into a complex, self-consistent tapestry. Because of the central role of Physics, we are best positioned to give our students the big picture.

Avoid Physics for Biologists or Physics for Engineers Weinberg provides one of the clearest arguments I have ever read against the relevance of astrology, telekinesis, creationism and other would-be sciences, as he politely refers to them. Why do scientists feel completely free to ignore such subjects without even extending to them the courtesy of an examination? Weinberg argues: What [these people] are missing is the sense of the connectedness of scientific knowledge. We do not understand everything, but we understand enough to know that there is no room in our world for telekinesis or astrology. What possible

physical signal from our brains could move distant objects and yet have no effect on any scientific instruments? . . . In fact, I do not think that most people who believe in astrology imagine that it works the way it does because of gravitation or any other agency within the scope of physics; I think they believe that astrology is an autonomous science, with its own fundamental laws, not to be explained in terms of physics or anything else. One of the great services provided by the discovery of the pattern of scientific explanation is to show us that there are no such autonomous sciences. Pedagogy in Physics 207 On-line tutorial in elementary scientific mathematics

Pre-lecture PowerPoint shows containing announcements, physics news, trivia, humor Transparency notes mixed with in-class polling Demonstrations (2-3 / lecture) >100 PowerPoint shows illustrating applications Cooperative learning sessions Labs tightly coupled with lecture Pedagogy in Physics 207 Pre-lecture PowerPoint shows containing announcements, physics news, trivia, humor

Transparency notes mixed with in-class multiple choice questions Demonstrations PowerPoint shows illustrating applications Cooperative learning sessions Labs tightly coupled with lecture If you miss work because of illness: Get a note from your doctor and give it to your TA. Make up missed lab work the same week in another lab. Have the lab TA sign your yellow

sheet. If you cannot make up the lab that week, obtain data from another student and turn in your own analysis of the data. Indicate the source of your data. Do missed homework, coop problems and turn them in, even if they are late. You'll get partial credit even if you don't have a note, provided they're not too late. Thank goodness youre here. I cant accomplish anything without a

deadline. Assignment 1 is due today. International News: Berlin - German opinion polls predict that the country will elect its first chancellor trained in the natural sciences later this month. A victory for the Christian Democratic Union on September 18 over the ruling Social Democrats would mean a government led by Angela Merkel, who holds a Ph.D. in physical chemistry. She

would also be the countrys first female chancellor. International News: The influential newspaper Seddeutsche Zeitung wrote that Merkel had demonstrated both meticulousness and tenacity in her 1986 dissertation on the calculation of rate constants in hydrocarbon decomposition

reactions. Such qualities, the paper said, could be usefully applied to the equally complex problems facing Germany. Science, 2 Sept. 2005 Todays Trivia To play some parts of an etude by Chopin, a pianist needs to be able to read and play 3,950 notes in two and a half minutes =150 seconds. Average notes/second ~ 26 Average time to play each note

~ 0.038 s Speed of neural impulses down the arm ~ 80 m/s ~ 180 mi/h Time to travel from brain to finger ~ 0.015 s He was expected to read a lecture on mathematics (broadly construed) each week during the academic term and deposit a copy in the university library. But he disregarded

this obligation far more than the fulfilled it. When he did lecture, students were scarce. Sometimes he read to bare room or gave up and walked back to his chambers. Isaac Newton by James Gleick What role does thermal expansion play in forming the Taugannock Amphitheatre? Pedagogy in Physics 207 Pre-lecture PowerPoint shows containing announcements, physics news, trivia, humor

Transparency notes mixed with in-class multiple choice questions (interactive learning / peer instruction) Demonstrations PowerPoint shows illustrating applications Cooperative learning sessions Labs tightly coupled with lecture Which of the following v-t graphs best describes the horizontal motion of a foot relative to the ground during ordinary walking? v t

v t v t v t (1) (2) (3)

(4) An object is thrown on flat ground at some angle with respect to the horizontal. How does the time for the object to reach the apex of its flight compare with the time for it to fall from the apex to the ground? time going up / time going down = ? 1. 1/2

2. 1/2 3. 1 4. 2

5. 2 An object is thrown on flat ground at some angle with respect to the horizontal. The object rises to a vertical height y max before returning to the ground. During its flight, how does the time the object spends with y>ymax/2 compare with the time it spends with y

2. The same. 3. More time in upper part. T1/T3=? 1.

1/3 2. 1/2 3. 1 1 m

2 m 3 4. 2 5. 3

m F a=0 m m 2

3 m F 2 m 1

1 m No friction 3 m In both cases, T1/T3 = 3

If we add more masses, eventually rope 1 will break. Coal trains The spring has stretched an amount x. What is the angle ? (Assume the surface on which the mass slides is frictionless.) k x m

=? 1. sin-1 (kx/mg) 2. sin (kx/mg) 3.

cos-1(kx/mg) 4. cos (kx/mg) The spring has stretched an amount x. What is the acceleration a? (Assume the surface on which the mass m slides is frictionless.) x

k a a=? 1. a=kx/m 2. a=k x m

3. a=kx 4. Insufficient information m Otolith Organ

fluid (provides damping) otolith (dense CaCO3) flexible tissue containing stretch-sensitive sensory cells (acts like spring) All vertebrates have at least 2 or 3 in each ear.

Measures orientation and acceleration. otolith fluid flexible tissue Detecting orientation: Detecting acceleration:

a Which of the following best describes the force vs. displacement (F-x) curve for an earlobe? F F (1)

x F (2) x F (3)

x (4) x Aortic Aneurysm: Why do Tennis Nets Sag?

T T T=? 1. mg

2. mg /sin() 3. mg / cos() 4. mg / 2 sin()

5. mg / 2 cos() m T

As 0 (i.e., the ropes approach horizontal), T? 1. 0 2. mg / 2 3.

mg 4. 2mg 5. T

m Other Applications sag of power lines power line and pole snapping by trees, ice plucking of guitar strings retrieving your car from a ditch How does the drag force exerted on a cyclist moving at v=55 km/h compare with the force exerted on a cyclist moving at v=27 km/h?

D (55 km/h) / D (27 km/h) ? (1) 1/4 (2) 1/2 (3) 1

(4) 2 (5) 4 Air Drag in Cycling: D = (1/2) C A v2 World Speed Records:

200 m, flying start: 71.3 km/h (~45 mi/h) 1 hour: 55.3 km/h (~35 mi/h) Air Drag in Cycling: D = (1/2) C A v2 How fast could you cycle if you could eliminate air drag?

Bonneville Salt Flats, Utah: Bonneville Salt Flats, Utah: John Howard, USA, 1985: 152 mi/h Fred Rompelberg, NL, 1995: 167 mi/h

(Rompelberg was 50 years old at the time.) Bird Formations During Migration: By taking advantage of upward moving air produced by their neighbors, migrating birds traveling in Vees" can travel 1.7 as far as individual birds. (~40% energy savings/mile). Fish Schools By swimming in synchrony in the correct formation,

each fish can take advantage of moving water created by the fish in front to reduce drag. Fish swimming in schools can swim 2 to 6 times as long as individual fish. Summary Physics is interesting and powerful, but its also hard! Pay attention to emotional needs. Show them why physics is relevant to what they care about themselves and their futures.

Teach in a way that helps develop confidence and promotes future inquiry F2 pivot L2 For rotational equilibrium, F2/F1 = ? 1.

1 2. -1 3. L1/L2 4.

L2/L1 F1 L1 F1 pivot L1

L3 L2 F2 For rotational equilibrium, F2/F1 = ? 1. 1

2. -1 3. L1/L2 4. L2/L1

Levers in Kitchen Utensils: L1 L2 Levers in Kitchen Utensils: L2 L1

Typical mechanical advantage: F2/F1=L1/L2: ~5 Maximum hand grip force: ~ 10 - 200 lb Maximum utensil force: ~ 50 - 1000 lb

Levers in Hydraulic Machines: How to throw a ball at 50 m/s using molecules that move at 10-5 m/s: 1. Start with basic unit: sarcomeres made of opposed actin filaments and myosin "motors" that pull filaments together. L~2.5 m, shortens by L/L ~ 40% in ~0.1 s How to throw a ball at 50 m/s using molecules that move at 10-5 m/s:

2. Connect sarcomeres in parallel to get big force F (up to 10,000 N!) Connect sarcomeres in series to get big L, L (up to 0.1 m) vmax (muscle) < 1 m/s How to throw a ball at 50 m/s using molecules that move at 10-5 m/s: 3. Use tendons (with dtendon << dmuscle) to connect muscles close to pivot points of long bones. Mechanical disadvange then produces large limb displacements for given muscle L. vrel,max (limb) ~ 5-10 m/s

How to throw a ball at 50 m/s using molecules that move at 10-5 m/s: 4. Use several mechanical "stages" that can rotate or move relative to each other. (E.g., legs, hips, torso, arms, wrists, fingers). 5. Execute relative motion of each stage so that

relative velocities of each stage add. "Whiplike" motion taking advange of elastic energy storage and release by tendons and ligaments maximizes impulse delivered to the ball. Speed of body parts relative to ground during a shot-put: Speed (m/s) Time before release (s) Summary

Physics is interesting and powerful, but its also hard! Pay attention to emotional needs. Show them why physics is relevant to what they care about themselves and their futures. Teach in a way that helps develop confidence and promotes future inquiry Pi what squared? Long John, you should be able to get this.

Syllabus Describing motion along a line: x, v, a relations Motion in a plane; projectile motion Newton's laws and forces; free-body diagrams Circular motion; friction and fluid drag Energy; kinetic energy, potential energy; power Oscillations: free, driven, damped Momentum and impulse; collisions; center of mass Torques and static equilibrium; elasticity Heat; thermal expansion; heat capacity; heat transport Static fluids: pressure, buoyancy, surface tension Moving fluids: continuity, Bernoulli, viscous drag and flow

Traveling and standing waves If you miss work because of illness: Get a note from your doctor and give it to your TA. Make up missed lab work the same week in another lab. Have the lab TA sign your yellow sheet. If you cannot make up the lab that week, obtain data from another student and turn in your own analysis of the data. Indicate the source of your data. Do missed homework, coop problems and

turn them in, even if they are late. You'll get partial credit even if you don't have a note, provided they're not too late. Polling in Physics 207 Each weeks questions are distributed in lecture at the start of the week, so students can work ahead. Questions are presented and solved on transparencies. Polling via a home built system (in use since 1972!) Questions are interleaved with demonstrations and applications.

Powerpoint applications projected on a separate screen. Polling in Physics 207 Emphasize transferable skills: graphical representations dimensional analysis proportional reasoning orders of magnitude and estimation approximate models Thank goodness youre here. I

cant accomplish anything without a deadline. Assignment 1 is due today. International News: Berlin - German opinion polls predict that the country will elect its first chancellor trained in the natural sciences later this month. A victory for the Christian Democratic Union on September 18 over the ruling Social Democrats would mean a

government led by Angela Merkel, who holds a Ph.D. in physical chemistry. She would also be the countrys first female chancellor. International News: The influential newspaper Seddeutsche Zeitung wrote that Merkel had demonstrated both meticulousness and tenacity in her 1986

dissertation on the calculation of rate constants in hydrocarbon decomposition reactions. Such qualities, the paper said, could be usefully applied to the equally complex problems facing Germany. Science, 2 Sept. 2005 Todays Trivia To play some parts of an etude by Chopin, a pianist needs to be able to read and play 3,950 notes in two and a half minutes =150 seconds. Average notes/second ~ 26

Average time to play each note ~ 0.038 s Speed of neural impulses down the arm ~ 80 m/s ~ 180 mi/h Time to travel from brain to finger ~ 0.015 s He was expected to read a lecture on mathematics (broadly construed) each week

during the academic term and deposit a copy in the university library. But he disregarded this obligation far more than the fulfilled it. When he did lecture, students were scarce. Sometimes he read to bare room or gave up and walked back to his chambers. Isaac Newton by James Gleick What role does thermal expansion play in forming the Taugannock Amphitheatre? Pedagogy in Physics 207

Pre-lecture PowerPoint shows containing announcements, physics news, trivia, humor Transparency notes mixed with in-class multiple choice questions (interactive learning / peer instruction) Demonstrations PowerPoint shows illustrating applications Cooperative learning sessions Labs tightly coupled with lecture An object moves along the x axis as shown below.

x t4 t1 t2 t3 At what time is v=0? 1. t1

2. t2 3. t3 4. t4

5. t5 t5 t Which of the following v-t graphs best describes the horizontal motion of a foot relative to the ground during ordinary walking? v

t v t v t v t (1) (2)

(3) (4) A car accelerates on a level road. What force acting on the car produces its acceleration? 1. The force of the engine on the wheels 2. The static friction force of the tires on the road 3. The static friction force of the road on the tires 4. The kinetic friction force of the tires on the road

A car of mass m traveling at a speed v is braked to a stop by a constant force F. If the initial speed of the car is doubled, by what factor does its stopping distance d change? d(2v)/d(v) = ? 1. 1/4 2. 1/2

3. 1 4. 2 5. 4

Pedagogy in Physics 207 Pre-lecture PowerPoint shows Transparency notes mixed with in-class multiple choice questions Demonstrations PowerPoint shows illustrating applications of physics Cooperative learning sessions Labs tightly coupled with lecture Making Physics Relevant

Most students are not "true believers in physics, and take the course only because it is required. Many have little idea of why or how physics may be relevant to their future careers. Many students continue to view physics as irrelevant even after taking high school and college physics courses. How can we introduce the applications of physics, in a way that motivates inquiry and promotes broader content knowledge?

- homework assignments - demonstrations - term papers / projects - in class via interactive mini-lectures Interactive Mini-Lectures Discuss applications of physics that are generally familiar in everyday life, or that are of particular interest to your students. Use a light touch, emphasizing basic ideas from class rather than detailed calculations. Use PowerPoint to provide a consistent

feel" and a smoother transfer of information. Interactive Mini-Lectures Use applications to illustrate how the same concepts crop up in completely different contexts. Cover multiple applications per class. Try to give a sense of the interconnectedness of science, of how phenomena and theory in distinct areas are interleaved into a complex, self-consistent tapestry.

Because of the central role of Physics, we are best positioned to give our students the big picture. Outcome: 1991-1998 Fall 1999 Fall 2006 Lecture 3.2 3.5

4.1 Course 3.0 3.3 3.8 Class time is very limited, so stay "on message." Keep the students focused on physics. Begin class promptly, and avoid speaking in class about anything except the material

being taught. Use handouts, course web pages/email lists and pre-class Powerpoint shows for announcements. Demonstrations are an essential tool for illustrating concepts. But most students can't follow the physics of many standard demonstrations. Select demos carefully. Perform those that are easy to understand, connect to everyday experience, and/or that are particularly

illustrative of a fundamental concept. Interactive Mini-Lectures Use applications to illustrate how the same concepts crop up in completely different contexts. Cover multiple applications per class. Try to give a sense of the interconnectedness of science, of how phenomena and theory in distinct areas are interleaved into a complex, self-consistent tapestry. Discuss real-world applications that are

straightforward extensions of fundamental ideas. To allow more applications to be presented in a given time, emphasize concepts, not math, and use pre-prepared transparencies or powerpoint. Math Skills for Intro Physics (Science!) Sketching and properties of simple functions. E.g, x, x2, x3, ax+bx2+cx3, 1/x, 1/x2, 1/(1-x), 1/(1x2). Sines and cosines. E.g., A cos(t + ). Graphing with arbitary A, , . Units and dimensional analysis. Showing that

equations have consistent dimensions. Using dimensions of variables to determine relations between variables. Orders of magnitude. What is an "order of magnitude"? An "order of magnitude" estimate? A feeling for the relative magnitudes of physical quantities (e.g., speeds of objects in m/s). "Back of the envelope" calculations. Exponentials exp(t/). Graphing. Meaning of the "time constant", relation to doubling time, halflife, decade time. What do "exponentially increasing" and "exponentially decreasing"

mean? Does an exponential increase faster than x? x2? x3? Proportions. Using proportions to make predictions based on measurements. E.g., if y = A x3, by what multiplicative factor will y change by if x is doubled? Algebra. General algebraic manipulations. Solving two equations in two unknowns. Geometry. Slopes, tangents, relations between interior and exterior angles. Areas of rectangles, triangles, trapezoids and circles. Volumes of

cubes, pyramids, spheres and cylinders. Surface to volume ratios; circumference to area ratios. Logs. Basic relations and graphing. Numerical relation between a value and its log. Semi-log plots. Generating them from a data set. Using semi-log plots to determine if a given data set has an exponential dependence; extracting the time constant. Log-log plots. Using log-log plots to determine power-law relations between x and y, e.g., y = A

x3. Allometry and scaling. Calculus. Basic notions of integrals and derivatives. Obtaining integrals and derivatives from data in tabular or graphical form; derivative = slope of curve at a point, integral = area under curve between two points. Numerical differentiation and integration. Derivatives and integrals of simple functions: x, x2, 1/x, A sin (t + ), Aexp(-t/). Solution (????):

Web-based math tutorial and evaluation tool. 1. A pre-test, whose completion is required for initial entry into the site. The student will be given their score and the required passing score. 2. Multiple choice or fill-in-the-blanks questions organized by topic, in the order they appear in the course. Include interactive questions. 3. Concise tutorial explanations (including motivation for why scientists require these skills

and how they use them), which can be viewed directly or via links from questions. 4. Unit tests on each major topic. 5. A set of comprehensive post-tests comparable to the pretest, to allow evaluation of learning outcomes. 6. A set of more rigorous tests for students who want to achieve a greater level of mastery. Parallel and interlinked math and physics question tracks Track 1: pure symbolic math

E.g. y=ax2. If we double y, by what factor does x change?) Track 2: Math with physical quantities, symbols and equations used in P207 E.g., the inward acceleration of an object moving in a circle is related to its speed and the radius of the circle by a=v2/r. If we double v, by what factor does a change? Pedagogy in Physics 207 Pre-lecture PowerPoint shows Transparency notes mixed with in-class multiple

choice questions Demonstrations PowerPoint shows illustrating applications of physics Cooperative learning sessions Labs tightly coupled with lecture How can we introduce the applications of physics, in a way that motivates inquiry and promotes broader content knowledge? - homework assignments - demonstrations

- term papers / projects - in class via interactive mini-lectures Interactive Mini-Lectures Discuss applications of physics that are generally familiar in everyday life, or that are of particular interest to your students. Use a light touch, emphasizing basic ideas from class rather than detailed calculations. Use PowerPoint to provide a consistent feel" and a smoother transfer of information.

How does the force that Darling the daughter exerts on Kitty the cat compare with the force that Kitty exerts on Darling? 1. FDarling on Kitty > FKitty on Darling 2. FDarling on Kitty = FKitty on Darling 3.

FDarling on Kitty < FKitty on Darling The Powder River Basin is the worlds largest coal producing region. 200 miles of coal trains leave the Powder River Basin every day, 365 days a year, bound for electricity generating plants. Trains can be up to 2 miles long, and weigh 23,000 tons. A flat-bed truck traveling at speed v carries a large spool of wire of

mass m. The truck swerves to avoid hitting a stalled car directly ahead, and in so doing executes an arc of radius r. If the coefficient of friction between the spool and the truck bed is s, what is the minimum radius r of the truck's turn for which the spool will not slip? stalled car rmin = ? (1) m v2 / g

(2) s g / v2 (3) v / s g 2 r truck spool

mass m v Suppose that the mass m of the spool of wire is doubled. By what factor does the minimum turn radius change? rmin (2m) / rmin (m) = ? (1) 1/4

(2) 1/2 (3) 1 (4) 2

(5) 4 stalled car r truck spool mass m v

A car accelerates on a level road. What force acting on the car produces its acceleration? 1. The force of the engine on the wheels 2. The static friction force of the tires on the road 3. The static friction force of the road on the tires 4. The kinetic friction force of the tires on the road Levers in Kitchen Utensils: From a fortune cookie consumed

at a local Chinese Restaurant: