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Making Introductory Physics More Like Real Physics.

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Making Introductory Physics More Like Real Physics Ruth Chabay & Bruce Sherwood Department of Physics North Carolina State University
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Making Introductory Physics More Like Real Physics Ruth Chabay & Bruce Sherwood Department of Physics North Carolina State University This venture was subsidized to a limited extent by the National Science Foundation (gifts MDR-8953367, USE-9156105, DUE-9954843, and DUE 9972420). Sentiments communicated are those of the creators, and not so much those of the establishment.

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Two Big Ideas The nuclear way of matter, quantum material science, and relativity must be integral to the initial course Change the substance , not singularly the instructional method The solidarity of physical science Students ought to be directed to see plainly that a couple of crucial standards clarify an extensive variety of marvels

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What would it be advisable for us to educate? Material science training research: an expansive venture by instructors and understudies is needed for compelling learning. What is sufficiently imperative to be justified regardless of an expansive speculation with respect to understudies and educators? Need clear objectives on which to base choices.

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Goals Involve understudies in the contemporary physical science undertaking: Emphasize a little number of crucial standards (unification of mechanics & warm physical science; electrostatics & circuits) Integrate twentieth century physical science (nuclear perspective; associations with science, science, materials science, nanotechnology, electrical building, atomic designing, PC designing, …) Engage understudies in physical displaying (glorification, close estimation, suppositions, estimation) (And, stay away from basic reiteration of secondary school physical science)

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Supporting materials: Matter & Interactions I: Modern mechanics; coordinated warm material science Matter & Interactions II: Electric & Magnetic Interactions present day E&M; physical optics John Wiley & Sons, 2002

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Matter & Interactions I: Modern Mechanics II: Electric & Magnetic Interactions Small number of basic standards Physical and PC demonstrating Atomic nature of matter: large scale/miniaturized scale Unification of points Just-in-time desktop tests Visualization/recreation programming

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Fundamental Principles Modern Mechanics: The force guideline The vitality rule The precise energy rule The essential suspicion of factual mechanics How would we make these seem key to the understudy?

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The Momentum Principle Not focal in customary educational modules; comes late in course In M&I , begin with Concept fundamental to the whole course

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The Momentum Principle: Approximations When would we be able to estimated p ≈ mv? To begin with unequivocal close estimation experienced by most understudies One segment of building physical models

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The Momentum Principle: The Newtonian Synthesis Initial conditions + rule + power law  iterative redesign of energy and position (time-advancement) One or two stages: on paper Orbits, oscillators, dissipating: PC projects composed by understudies Less accentuation on deriving powers from known movement

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The Momentum Principle: Running understudies crash NEAR rocket experiences Mathilde space rock Finding dim matter Black opening at galactic focus Diatomic particle vibration Momentum + Energy Principles: Fusion Producing the D +

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In 1997 the NEAR shuttle went inside 1200 km of the space rock Mathilde at a pace of 10 km/s in respect to the space rock ( Photographs transmitted by the rocket show Mathilde’s measurements to be around 70 km by 50 km by 50 km. It is apparently made out of rock; rock on Earth has a normal thickness of around 3000 kg/m 3 . The mass of the NEAR rocket is 805 kg. A) Sketch subjectively the shuttle's way: B) Make a harsh assessment of the adjustment in energy of the rocket coming about because of the experience. Clarify how you made your assessment. C) Estimate the avoidance (in meters) of the spacecraft’s direction from its unique straight-line way, one day after the experience. D) From real perceptions of the shuttle's position one day in the wake of experiencing Mathilde, researchers presumed that Mathilde is a free course of action of rocks, with heaps of unfilled space inside. Shouldn't something be said about the perceptions probably driven them to this conclusion? (week 2)

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The Momentum Principle: Atomic Nature of Matter Ball-and-spring model of strong Macro-smaller scale association (Young’s modulus - interatomic spring consistent) Apply force rule to model spread of sound in a strong; focus rate of sound

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Week 3: An example week

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Chapter 3 The Atomic Nature of Matter: Modeling a Solid Day 1 (recitation) Measurements (a) Properties of spring-mass frameworks: Students measure k s , T , m for a mass and spring (b) Properties of solids: Students measure Young’s modulus for aluminum

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Chapter 3 The Atomic Nature of Matter: Modeling a Solid Day 2 (address) Ball-and-spring model for a strong; application to an extended wire (a) Students figure powerful interatomic spring solidness k s from Young’s modulus for Al and Pb (b) Newton’s second law connected to a mass on a flat spring

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Chapter 3 The Atomic Nature of Matter: Modeling a Solid Day 3 (recitation) Students compose a PC program: (a) Model the movement of a mass on a spring, utilizing day 1 information (numerical coordination of Newton’s second law) (b) Display an activity of the movement and a diagram of x versus . t (c) Compare measured period and processed period (great assention).

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Chapter 3 The Atomic Nature of Matter: Modeling a Solid Day 4 (address) Analytical answer for spring-mass framework Students anticipate period for: 2 masses versus 1 mass 2 springs versus 1 spring 1 spring 2x as long, and so on. Test students’ expectations with demos

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Chapter 3 The Atomic Nature of Matter: Modeling a Solid Day 5 (address) Atomic association: static (Young’s modulus) and element (velocity of sound in a strong) Demo: measure rate of sound in bar of aluminum Students plan PC project to foresee pace of sound, in light of ball & spring model of a strong Run PC model (long chain of masses & springs), utilizing k s for Al & Pb computed by understudies amid past address Dimensional investigation: v =

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In a prior issue we discovered the compelling spring consistent comparing to the interatomic power for aluminum and lead. Let’s accept for the minute that, generally, different molecules have comparative qualities. (a) What is the (exceptionally) surmised recurrence f for the vibration of H 2 , a hydrogen atom? (b) What is the (extremely) rough recurrence f for the vibration of O 2 , an oxygen atom? (c) What is the surmised vibration recurrence f of D 2 , a particle both of whose iotas are deuterium molecules (that is, every core has one proton and one neutron)? (d) Why is the deuterium's proportion recurrence to the hydrogen recurrence entirely exact, despite the fact that the powerful spring consistent is typically anticipated that would be fundamentally distinctive for diverse iotas? (Clue: what association is demonstrated by the compelling “spring”?)

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In my feeling, the focal thought in this section was to discover that iotas attached to one another can be considered as two balls joined with each other with a spring. When we comprehended this idea, we could apply the models of springs from the plainly visible world to the nuclear level, which gave us a general thought of how things work at the nuclear level. Understanding that gave us the capacity to anticipate vibrational frequencies of diatomic particles and sound proliferation in a strong. It is totally astounding how we can utilize exceptionally basic ideas and thoughts, for example, force and spring movement to infer a wide range of stuff from it. I really like that about this course. (S.H.)

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The most focal idea we’ve utilized is Newton’s second law. I have never utilized energy this much ever. Some way or another - it functions as the characterizing variable of each mathematical statement or equation of movement to characterize how protests move and communicate with one another. The most astounding thing to me, on the other hand, is not so much the law- - but rather how critical one single idea can be in such a large number of fluctuated issues. (J.H.)

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Week 14: Ball and spring model of a strong (Einstein model: free quantized oscillators): understudies compose a PC system to ascertain the warmth limit of a strong as a component of temperature. Understudies fit bends to real information for Pb and Al, with one parameter, the interatomic spring steady k s . Qualities got are predictable with results from Week 3. Understudies measure heat limit of water in a microwave stove. heat limit

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Modeling Physical Systems Explain, anticipate, comprehend untidy true marvels Start from key standards Idealize: Decide how to model a framework Make suppositions and rough guesses Estimate amounts Analyze a little number of wonders, not countless issues

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A hot bar of iron shines a dull red. Utilizing our straightforward model of a strong, answer the accompanying inquiries. The mass of one mole of iron is 56 g. (a) What is the vitality of the most minimal vitality unearthly outflow line? (Give a numerical worth). (b) What is the rough vitality of the most astounding vitality otherworldly emanation line? (c) What is the quantum number of the most elevated vitality possessed state? (d) Predict the energies of two different lines in the emanation range of the sparkling iron bar. (Note: the genuine range is more perplexing than this, and a more mind boggling model is obliged to clarify it in subtle element.) (week 7)

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Research Supporting Development Theoretical New perspectives of standard material science Cognitive assignment examinations Predictions in view of models of learning Experimental Analysis of students’ composed work Think-out loud convention investigation (feature) Fine-