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General Physics I: Mechanics, Heat, and Sound Course Structure

Explore fundamental physics concepts through lectures, demonstrations, and laboratory sessions. Engage with scientific method, laws of physics, and more. Gain insight into the world of physics and develop analytical skills.

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General Physics I: Mechanics, Heat, and Sound Course Structure

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  1. Physics 350General Physics I:Mechanics, Heat and Sound

  2. Course Structure • Full class meets 2 times per week in FL2-208 • MW 5:30–6:50 PM • Lectures • PowerPoint presentations • Lecture materials will be made available on the web • Work out example problems and questions • Demonstrations • Laboratory section meets twice a week following lecture • MW 7:00–8:20 PM: FL2-208 • Opportunity for discussions on course material, exam prep, etc.

  3. Resources • Your Fellow Students! • Encouraged to work together on homework, exercises (but not on exams!) • Tutoring: Tutoring center located in Aspen Hall room FL1-108 or the Reading, Writing, and Math Center at Cypress Hall FL2-239 • Instructor! • Office in FL2-208, office hours F 4:00 PM – 5:00 PM, or by appointment mondays@flc.losrios.edu • Web: flc.losrios.edu/~mondays • Lecture presentations, updates, HW assignments/solutions • Text • Physics, Sixth Edition, Giancoli

  4. Course Objectives • Explore the approach that physics brings to bear on the world around us • Scientific Method • Quantitative Models • Reductionism

  5. Course Objectives, continued • Appreciate the influence physics has on us all • Begin to see physics in the world around you • Develop your natural intuition, stimulate curiosity • Think into the unknown (ooh that’s scary!) • Understand basic laws of physics • Newton’s laws of motion, gravitation • Concepts of mass, force, acceleration, energy, momentum, power, etc. • Fluid mechanics, mechanical waves (including sound), and thermodynamics.

  6. What’s with these questions/observations? • Science is as much about questions as answers. • You may have questions about: • Something you’ve always wondered about • Something you recently noticed • Something that class prompted you to think about • Goal is to increase your awareness, observational skills, analytical skills • We’re immersed in physics: easy to ignore, but also easy to see! • You’ll begin to think more deeply before shoving problem aside • Allow your natural curiosity to come alive

  7. Expectations • Attend lectures and laboratory section • Participate! • If it doesn’t make sense, ask! Everyone learns that way. • Don’t be bashful about answering questions posed. • Do the work: • It’s the only way this stuff will really sink in • exams become easier • Explore, think, ask, speculate, admire, enjoy! • Physics can be fun

  8. Does it Pay to Come to Lecture? • No one who came more than 80% of time did very poorly • Few who came infrequently got more than a low B

  9. Any Questions on Course Structure?

  10. What is “Physics” • An attempt to rationalize the observed Universe in terms of irreducible basic constituents or simplest form, interacting via basic forces. • Reductionism! • An evolving set of (sometimes contradictory!) organizing principles, theories, that are subjected to experimental tests. • This has been going on for a long time.... with considerable success

  11. Kepler’s laws of planetary motion Falling apples Universal Gravitation “Unification” of forces Reductionism • Attempt to find unifying principles and properties e.g., gravitation:

  12. Should we even pay attention, then? • Physics is always on the move • theories that long stood up to experiment are shot down • But usually old theory is good enough to describe all experiments predating the new trouble-making experiment • otherwise it would never have been adopted as a theory • Ever higher precision pushes incomplete theories to their breaking points • Result is enhanced understanding • deeper appreciation/insight

  13. Mathematics: the natural language of Physics Engineering Biology Geology Chemistry Astronomy Physics Physical Reality Our Universe Abstraction Mathematics Logic, Numbers, Operators

  14. To Start: • First Up – Review • Next Lectures – Kinematics • Assignments: • Check out course web page: • flc.losrios.edu/~mondays • Reading: • Giancoli, Chapter 1

  15. Physics 350Chapter 1: Review

  16. Review: • Units • Any measurement or quantitative statement requires a standard to compare with to determine its quantity • If I go a speed of 30, how fast am I going? • Mi/hr. km/hr, ft/sec • Units help us to quantify against a known standard

  17. Measurements • Basis of testing theories in science • Need to have consistent systems of units for the measurements • Uncertainties are inherent • Need rules for dealing with the uncertainties

  18. Systems of Measurement • Standardized systems • agreed upon by some authority, usually a governmental body • SI -- Systéme International • agreed to in 1960 by an international committee • main system used in this course • also called mks for the first letters in the units of the fundamental quantities

  19. Systems of Measurements • cgs -- Gaussian system • named for the first letters of the units it uses for fundamental quantities • US Customary • everyday units (ft, etc.) • often uses weight, in pounds, instead of mass as a fundamental quantity

  20. Basic units • Three basic quantitative measurements • Length • Mass • Time • All units can be reduced to these three units!

  21. Length • Units • SI -- meter, m • cgs -- centimeter, cm • US Customary -- foot, ft • Defined in terms of a meter -- the distance traveled by light in a vacuum during a given time (1/299 792 458 s)

  22. Mass • Units • SI -- kilogram, kg • cgs -- gram, g • USC -- slug, slug • Defined in terms of kilogram, based on a specific Pt-Ir cylinder kept at the International Bureau of Standards

  23. Standard Kilogram

  24. Time • Units • seconds, s in all three systems • Defined in terms of the oscillation of radiation from a cesium atom (9 192 631 700 times frequency of light emitted)

  25. Time Measurements

  26. US “Official” Atomic Clock

  27. 2. Dimensional Analysis • Dimension denotes the physical nature of a quantity • Technique to check the correctness of an equation • Dimensions (length, mass, time, combinations) can be treated as algebraic quantities • add, subtract, multiply, divide • quantities added/subtracted only if have same units • Both sides of equation must have the same dimensions

  28. Dimensional Analysis • Dimensions for commonly used quantities Length L m (SI) Area L2 m2 (SI) Volume L3 m3 (SI) Velocity (speed) L/T m/s (SI) Acceleration L/T2 m/s2 (SI) • Example of dimensional analysis distance = velocity · time L = (L/T) · T

  29. 3. Conversions • When units are not consistent, you may need to convert to appropriate ones • Units can be treated like algebraic quantities that can cancel each other out 1 mile = 1609 m = 1.609 km 1 ft = 0.3048 m = 30.48 cm 1m = 39.37 in = 3.281 ft 1 in = 0.0254 m = 2.54 cm

  30. Example 1. Scotch tape: Example 2. Trip to Canada: Legal freeway speed limit in Canada is 100 km/h. What is it in miles/h?

  31. Prefixes • Prefixes correspond to powers of 10 • Each prefix has a specific name/abbreviation Power Prefix Abbrev. 1015 peta P 109 giga G 106 mega M 103 kilo k 10-2 centi P 10-3 milli m 10-6 micro m 10-9 nano n Distance from Earth to nearest star 40 Pm Mean radius of Earth 6 Mm Length of a housefly 5 mm Size of living cells 10 mm Size of an atom 0.1 nm

  32. Example: An aspirin tablet contains 325 mg of acetylsalicylic acid. Express this mass in grams. Solution: Given: m = 325 mg Find: m (grams)=? Recall that prefix “milli” implies 10-3, so

  33. 4. Uncertainty in Measurements • There is uncertainty in every measurement, this uncertainty carries over through the calculations • need a technique to account for this uncertainty • We will use rules for significant figures to approximate the uncertainty in results of calculations

  34. Significant Figures • A significant figure is one that is reliably known • All non-zero digits are significant • Zeros are significant when • between other non-zero digits • after the decimal point and another significant figure • can be clarified by using scientific notation 3 significant figures 5 significant figures 6 significant figures

  35. Operations with Significant Figures • Accuracy -- number of significant figures • When multiplying or dividing, round the result to the same accuracy as the least accurate measurement • When adding or subtracting, round the result to the smallest number of decimal places of any term in the sum meter stick: Example: 2 significant figures rectangular plate: 4.5 cm by 7.3 cm area: 32.85 cm2 33 cm2 Example: Example: 135 m + 6.213 m = 141 m

  36. Order of Magnitude • Approximation based on a number of assumptions • may need to modify assumptions if more precise results are needed • Order of magnitude is the power of 10 that applies Question: McDonald’s sells about 250 million packages of fries every year. Placed end-to-end, how far would the fries reach? Solution:There are approximately 30 fries/package, thus: (30 fries/package)(250 . 106 packages)(3 in./fry) ~ 2 . 1010 in ~ 5 . 108 m, which is greater then Earth-Moon distance (4 . 108 m)! Example: John has 3 apples, Jane has 5 apples. Their numbers of apples are “of the same order of magnitude”

  37. Math Review: Trigonometry • Pythagorean Theorem

  38. Example: how high is the building? Known: angle and one side Find: another side Key: tangent is defined via two sides! a

  39. Math Review: Coordinate Systems • Used to describe the position of a point in space • Coordinate system (frame) consists of • a fixed reference point called the origin • specific axes with scales and labels • instructions on how to label a point relative to the origin and the axes

  40. Types of Coordinate Systems • Cartesian • Plane polar • Spherical • Cylindrical

  41. Cartesian coordinate system • also called rectangular coordinate system • x- and y- axes • points are labeled (x,y)

  42. Plane polar coordinate system • origin and reference line are noted • point is distance r from the origin in the direction of angle , ccw from reference line • points are labeled (r,)

  43. Relationship Between Polar and Rectangular Coordinates • Looking at the figure, we can see that leading to the relationship • This is how you would change polar coordinates to rectangular coordinates.

  44. Relationship Between Polar and Rectangular Coordinates • Looking at the figure, we can also see that • This is how you would change rectangular coordinates to polar coordinates.

  45. Example 1 • Find the rectangular coordinates of the point P whose polar coordinates are (6, 2p/3).

  46. Example 1 • Find the rectangular coordinates of the point P whose polar coordinates are (6, 2p/3). • Since r = 6 and q = 2p/3, we have

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