Chapter 1(2)INTRODUCTION TO PHYSICS
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The document discusses fundamental units in classical mechanics and provides examples of physical quantities measured in SI units. It introduces the seven base units of the International System of Units (SI) - meter, kilogram, second, ampere, kelvin, mole, and candela. Derived units like newton, joule, watt, and ohm are also mentioned. Standard prefixes are defined to denote multiples of ten when measuring very large or small quantities.
Chapter 1(2)INTRODUCTION TO PHYSICS
- 1. How we measure things! All things in classical mechanics can be expressed in terms of the fundamental dimension or unit: Dimension Unit Length L meter Mass M kilogram Time T second For example: Speed has dimension of L / T (i.e. miles per hour). Force has dimension of ML / T 2 etc... (as you will learn). CHAPTER 1: PHYSICAL QUANTITIES
- 2. Length: Distance Length (m) Radius of visible universe 1 x 10 26 To Andromeda Galaxy 2 x 10 22 To nearest star 4 x 10 16 Earth to Sun 1.5 x 10 11 Radius of Earth 6.4 x 10 6 Sears Tower 4.5 x 10 2 Football field 1.0 x 10 2 Tall person 2 x 10 0 Thickness of paper 1 x 10 -4 Wavelength of blue light 4 x 10 -7 Diameter of hydrogen atom 1 x 10 -10 Diameter of proton 1 x 10 -15
- 3. Time: Interval Time (s) Age of universe 5 x 10 17 Age of Grand Canyon 3 x 10 14 32 years 1 x 10 9 One year 3.2 x 10 7 One hour 3.6 x 10 3 Light travel from Earth to Moon 1.3 x 10 0 One cycle of guitar A string 2 x 10 -3 One cycle of FM radio wave 6 x 10 -8 Lifetime of neutral pi meson 1 x 10 -16 Lifetime of top quark 4 x 10 -25
- 4. Mass: Object Mass (kg) Milky Way Galaxy 4 x 10 41 Sun 2 x 10 30 Earth 6 x 10 24 Boeing 747 4 x 10 5 Car 1 x 10 3 Student 7 x 10 1 Dust particle 1 x 10 -9 Top quark 3 x 10 -25 Proton 2 x 10 -27 Electron 9 x 10 -31 Neutrino 1 x 10 -38
- 5. Units... SI (Système International) Units: mks: L = meters (m), M = kilograms (kg), T = seconds (s) cgs: L = centimeters (cm), M = grams (gm), T = seconds (s) Derived Units : Newton, Joule, Watt, Ohm …. and etc. British Units: Inches, feet, miles, pounds, slugs... fps : L = foot, M = pound, T = second We will use mostly SI units with mks system , but you may run across some problems (rarely happen) using British units. You should know how to convert back & forth.
- 6. The 7 International System of Units (SI) mol mol Amount of Substance cd candela Luminous Intensity K kelvin Temperature I ampere Electric current s second Time kg kilogram Mass m meter Length Symbol SI Units Quantity
- 7. Derived Units A 2 s 4 / (kg m 2 ) F Farad Capacitance kg m 2 / (s 2 A 2 ) H Henry Inductance Wb V C Pa W J N Abbreviation kg m 2 / (A s 2 ) Weber Magnetic Flux kg m 2 / (A s 3 ) Volt Electric Potential A s Coulomb Electric Charge kg / (ms 2 ) Pascal Pressure kg m 2 s -3 Watt Power kg m 2 s -2 Joule Energy & Work kg ms -2 Newton Force In terms of Base Units Unit Quantity
- 8. Standard Prefixes : used to denote multiple of ten 10 15 10 12 10 9 10 6 10 3 10 2 10 1 Factor Peta Tera Giga Mega kilo hecto deka Prefix P f femto 10 -15 a ato 10 -18 p n m m c d Symbol T pico 10 -12 G nano 10 -9 M micro 10 -6 k milli 10 -3 h centi 10 -2 da deci 10 -1 Symbol Prefix Factor
- 9. Standard Prefixes Example: The capacitance of a capacitor is measured to be 0.00000000000125842325976 F (Farad) 0.000000001258423…F 3 3 3 = 1.25842325976 X 10 -9 F = 1.25842325976 nF