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College Physics

College Physics. Introduction and Chapter 1. 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. Systems of Measurement. Standardized systems

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College Physics

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  1. College Physics Introduction and Chapter 1

  2. 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

  3. 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 text • also called mks for the first letters in the units of the fundamental quantities

  4. Basic Quantities and Their Dimension • Length [L] • Mass [M] • Time [T]

  5. Standard Kilogram

  6. Dimensional Analysis • Technique to check the correctness of an equation • Dimensions (length, mass, time, combinations) can be treated as algebraic quantities • add, subtract, multiply, divide • Both sides of equation must have the same dimensions

  7. 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

  8. Conversions • When units are not consistent, you may need to convert to appropriate ones • Units can be treated like algebraic quantities that can divide out • See the inside of the front cover for an extensive list of conversion factors How Fast is 1 m/s?

  9. Examples of various units measuring a quantity

  10. 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

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

  12. 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,)

  13. Trigonometry Review

  14. More Trigonometry • Pythagorean Theorem • To find an angle, you need the inverse trig function • for example,

  15. Fig. 1.7, p.14 Slide 15

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