ASTA02H3 Lecture Notes - Lecture 3: Gravitational Constant, Fundamental Interaction, Kelvin
Document Summary
Light is the only signal we get from far away galaxies. All interactions in nature are ruled by four fundamental forces: Obeys the inverse square law of distance: Gravitational constant: 6. 67408 10-11 m3 kg-1 s-2. Em force is very strong: 10^39 times stronger than gravity. Ordinary matter is found in the form of atoms. Atoms are mostly empty space; only 1 part in 10^15 of the volume is occupied, volume is threaded by electromagnetic fields. All elements interact with light in different ways. Different interactions: matter can transmit light (glass, water) matter can reflect light matter can gain/lose energy by absorbing/emitting light, respectively. Temperature: a measure of the internal energy content of an object. Solids: higher temperature means higher average vibrational energy per atom or molecule. Gases: higher temperature means more average kinetic energy (faster speeds) per atom or molecule. It is directly proportional to the amount of internal energy of an object.
