The Realm of Physics : The Realm of Physics Range of magnitudes of quantities in our universe 8/26/2011 1 AP Physics
What is physics? : What is physics? Physics is the study of the fundamental interactions of our universe. 8/26/2011 2 AP Physics
What does a physicist measure? : What does a physicist measure? length, mass, time, electric current, temperature, amount of substance, luminous intensity
area, volume, density, velocity, acceleration, force, energy, work, power, momentum, pressure, electric potential, conductivity, resistance, frequency, amplitude, activity, and on and on and on… 8/26/2011 3 AP Physics
Order of Magnitude : Order of Magnitude Devise a rough estimate of the number of molecules in the sun.
Mass of the sun = 1030 kg
Composed of 75% H, 25% He. For rough estimate: 100% H.
Molar mass of H: 2 x 10-3 kg/mol
Avogadro’s number: 6 x 1023 molecules/mol
3 x 1056 molecules! 8/26/2011 4 AP Physics
Some Interesting Lengths : Some Interesting Lengths 8/26/2011 5 AP Physics
Some Interesting Masses : Some Interesting Masses 8/26/2011 6 AP Physics
Some Interesting Time Intervals : Some Interesting Time Intervals 8/26/2011 7 AP Physics
Stop to Think… : Stop to Think… Calculate the following ratios:
Diameter of solar system / Distance from earth to sun
Size of hydrogen atom / Size of proton
Mass of sun / Mass of earth
Age of the universe / One day 8/26/2011 8 AP Physics
Range of Magnitudes : Range of Magnitudes Distances
10-15 m (sub-nuclear particles)
1025 m (extent of visible universe)
Masses
10-30 kg (electron)
1053 kg (mass of the universe)
Times
10-23 s (passage of light across atomic nucleus
1018 s (age of the universe) There has to be an easier way!!!! 8/26/2011 9 AP Physics
Metric Prefixes : Metric Prefixes * rarely used 8/26/2011 10 AP Physics
Fundamental Interactions : Fundamental Interactions Gravitational
Strong Nuclear Force (colour) Weak Nuclear Force Electromagnetic Electroweak (since 1972) 8/26/2011 11 AP Physics