Hello, knowledge points of physics exercises 1. The contents of molecular dynamics theory are as follows: (1) Matter is composed of molecules with gaps between them; (2) The molecules of all objects do random motion endlessly; (3) There is attraction and repulsion between molecules.

2. Diffusion: the phenomenon that different substances contact and enter each other.

3. When solid and liquid are compressed, the repulsion between molecules is greater than gravity. Solids are difficult to elongate because the attraction between molecules is greater than the repulsion.

4. Molecules are composed of atoms, atoms are composed of nuclei and extranuclear electrons, and nuclei are composed of protons and neutrons.

5. Thomson discovered electrons (1897); Rutherford discovered protons (1919); Neutron discovered in chadwick (1932); Gherman put forward the quark hypothesis (196 1 year).

6. Accelerator is a powerful weapon to explore tiny particles.

7. The Milky Way is a huge celestial system composed of stars and diffuse matter, and the sun is just one of ordinary stars.

8. The universe is a hierarchical celestial structure system. Most scientists believe that the universe was born in a big bang 654.38+0.5 billion years ago. This explosion is a whole, involving all matter, time and space in the universe. The explosion caused the universe to expand everywhere, and the temperature dropped accordingly.

I hope I can help you.