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How People Learn. Conclusion 1: Henri Poincaré “We must, for example, use language, and our language is necessarily steeped in preconceived ideas. Only.

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Presentation on theme: "How People Learn. Conclusion 1: Henri Poincaré “We must, for example, use language, and our language is necessarily steeped in preconceived ideas. Only."— Presentation transcript:

1 How People Learn

2 Conclusion 1: Henri Poincaré “We must, for example, use language, and our language is necessarily steeped in preconceived ideas. Only they are unconscious preconceived ideas, which are a thousand times the most dangerous of all.”

3 “Birds,” said the frog mysteriously. “Birds!” And he told the fish about the birds, who had wings, and two legs, and many many colors.

4 “Cows,” said the frog. “Cows! They have four legs, horns, eat grass and carry pink bags of milk.”

5 “And people,” said the frog. “Men, women, children!” And he talked and talked until it was dark in the pond.

6 Conclusion 2: Expert vs. Novice Learners Conclusion 3: Metacognition or reflection

7 1600 to 1900 Classical Physics Mechanics Thermodynamics Electromagnetism 1900 to 1940 Modern Physics Relativity Large speeds (  10 8 m/s). Quantum Mechanics Very small scales (  10 -10 m). 1940 to present Current Physics Particle Physics Cosmology Ch1-1 Physics and the Laws of Nature

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9 How Physics Works Model / Theory Observation / Experiment

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11 Length [L] meterDistance traveled by light in vacuum in 1 / 299792458 seconds Mass [M] kilogramMass of a platinum-iridium alloy kept in France at the International Bureau of Weights and Measures Time [T] second919263177 times the period of vibration of radiation from the Ce-133 atom Ch1-2 Units of Length Mass and Time Standards

12 Ch1-2 Standards of Length Mass and Time Standards A Force acts on a mass resulting in motion. M L,T

13 Distance from the Earth to the nearest large galaxy (the Andromeda Galaxy, M31) 2 x 10 22 m Diameter of our galaxy (the Milky Way)8 x 10 20 m Distance from the Earth to the nearest star (other than the Sun) 4 x 10 16 m One light year9.46 x 10 15 m Average radius of Pluto’s orbit6 x 10 12 m Distance from Earth to the Sun1.5 x 10 11 m Radius of Earth6.37 x 10 6 m Length of football field10 2 m Height of a person2 m Diameter of a CD0.12 m Diameter of the aorta0.018 m Diameter of the period in a sentence5 x 10 –4 m Diameter of a red blood cell8 x 10 –6 m Diameter of the hydrogen atom10 –10 m Diameter of a proton2 x 10 –15 m Ch1-2 Standards of Length Mass and Time Typical Lengths

14 Scales

15 Galaxy (Milky Way)4 x 10 41 kg Sun2 x 10 30 kg Earth5.97 x 10 24 kg Space Shuttle2 x 10 6 kg Elephant5400 kg Automobile1200 kg Human70 kg Baseball0.15 kg Honeybee1.5 x 10 –4 kg Red blood cell10 –13 kg Bacterium10 –15 kg Hydrogen atom1.67 x 10 –27 kg Electron9.11 x 10 –31 kg Ch1-2 Standards of Length Mass and Time Typical Masses

16 Ch1-2 Standards of Length Mass and Time Typical Times Age of the universe5 x 10 17 s Age of the Earth1.3 x 10 17 s Existence of human species6 x 10 13 s Human lifetime2 x 10 9 s One year3 x 10 7 s One day8.6 x 10 4 s Time between heartbeats0.8 s Human reaction time0.1 s One cycle of a high-pitched sound wave5 x 10 –5 s One cycle of an AM radio wave10 –6 s One cycle of a visible light wave2 x 10 –15 s

17 10 15 petaP 10 12 teraT 10 9 gigaG 10 6 megaM 10 3 kilok 10 2 hectoh 10 1 dekada 10 –1 decid 10 –2 centic 10 –3 millim 10 –6 micro  10 –9 nanon 10 –12 picop 10 –15 femtof PowerPrefixAbbreviation Ch1-2 Standards of Length Mass and Time Common Prefixes

18 Concept Question 1.1 (2.44 x 10 -5 ) / (2 x 10 3 ) = a.2.44 x 10 -8 b.2.44 x 10 -2 c.1.22 x 10 -8 d.1.22 x 10 2 e.1.22 x 10 8

19 Distance[L] Area[L 2 ] Volume[L 3 ] Velocity[L]/[T] Acceleration[L]/[T 2 ] Energy[M][L 2 ]/[T 2 ] QuantityDimension Ch1-2 Standards of Length Mass and Time Dimensions of Some Common Physical Quantities

20 Concept Question 1.2 Ch1-3 Dimensional Analysis Given the following definitions with their dimensions: v = velocity (L/T) a = acceleration (L/T 2 ) t = time (T) Which of the following equations could be correct as far as dimensions are concerned? A.v = at 2 /2 B.v = a/2t C.v = at D.v = a 2 t/2 E.v = a/t 2

21 How does v depend on a and x? P1.5 (p. 14) Suppose v 2 = 2ax p What is p? Ch1-3 Dimensional Analysis

22 Concept Question 1.3 Which statement is correct regarding significant figures? A.1.355 + 1.2 = 2.555 B.1.478 – 1.3 = 0.18 C.1.513 / 1.5 = 1.009 D.1.5 x 10 -3 + 0.1 = 0.1015 E.0.1513 x 1.5 = 0.23 Ch1-4 Significant Figures

23 Do P1.12 (p. 14) P = 2 l + 2 w Ch1-4 Significant Figures

24 Round-off: If next digit is  5, then round up. Scientific Notation: Covered previously. Ch1-4 Significant Figures

25 Concept Question 1.4 How many seconds in a 50 minute class period? A.1000 B.50 C.3 x 10 -3 D.4500 E.3 x 10 3 Ch1-5 Conversion of Units

26 Do P1.24 (p. 15) Ch1-5 Conversion of Units

27 CT1.5 A. 500 B. 5,000 C. 50,000 D. 500,000 Ch1-6 Order-of-Magnitude Calculations

28 Shea Stadium holds about 55,000.

29 CT1.6 Donovan Bailey – Canada – 1996 Olympics 1 2 3 4 5 Who is in 0.1 s of Donovan? A. 2,3,4,5 B. 2,3,4 C. 2,3 D. 2

30 Donavan is roughly 2 meters tall and that gives the scale. Since they covered 100 m in 10 seconds, each meter takes about 0.1 seconds. The answer is c because they are within roughly 1 meter (half Donovan’s height).

31 Estimate how many barbers in Chicago?

32 I started by assuming a typical person gets a haircut every two months. Next I assumed that a barber could give about 4 haircuts/hr or 20/day or 100/week or 400/month or 800/every two months. I rounded this off to about 500/every two months since there may be times when the barber doesn't have customers. So a barber could take care of about 500 customers and then they would all come back again. There are about 3 million people in Chicago proper and 8 million in the metropolitan area so I picked an average of 5 million to represent Chicago. That means about 5x10 6 / 500 or 10 4 or 10,000 barbers. This is just an estimate and may be off by a factor of 10 either way given all the questionable assumptions!

33 A Google search listed 1711 barbers around Chicago.

34 Ch1-7 Scalars and Vectors A scalar is a pure number. What are some examples? A vector has magnitude (value) and direction. What are some examples? The magnitude of a vector could be considered a scalar.

35 Ch1-8 Problem Solving Read the problem carefully. Sketch the system. Visualize the physical process. Strategize. Identify appropriate equations. Solve the equations. Check your answer. Explore limits and special cases.

36 Ch1-8 Problem Solving Do P1.39 (p. 16) N = number of beats B = beats/second T = time

37 Mechanics Study of forces and energy and motion. Force is an agent of change. Energy is a measure of change.


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