PHYS114 Lecture Notes - Lecture 1: Biophysics, Kilogram, Caesium
Document Summary
It seeks to u(cid:374)dersta(cid:374)d e(cid:448)erythi(cid:374)g (cid:449)e o(cid:271)ser(cid:448)e, fro(cid:373) the su(cid:271)ato(cid:373)i(cid:272) (cid:449)orld right up to the stru(cid:272)ture of the (cid:272)os(cid:373)os. (cid:863) Theory - intellectual framework used to explain those observations; has predictive value; must be testable. An impossible-to-measure statement is not a theory: basic wave properties. How to create a system of units: must be unchanging, universal, and reasonably convenient to use, the si system (based in france, base units (cannot be derived from other units) Second (time), meter, kilogram, ampere (electrical current), kelvin, mole, candela (a physiological reaction to brightness: derived units. Joule (derived from second, meter, and kg), watt, coulomb, ohm, newton, Length are identical: how do you define a meter, used to be defined as 1/10 000 000 distance between pole and equator - does(cid:374)"t (cid:449)ork because of tides, mountains, etc. Very inconvenient to measure: mid 1900s france created irpt metal bars to define a meter (constant, very stable) and tried to replicate them.
