Why is a kinetic theory called a kinetic theory not the kinetic law?

Answer 1

Some words have specialized meanings in science which are not exactly the same as their less formal general usage; this tends to confuse laypeople. A lot. "Law" is used for ideas that can be expressed as a single (though possibly complicated) equation or statement, such as Newton's Third Law of Motion F = ma. "Theory" is used for ideas that are more intricate and do not reduce to a single equation, such as Einstein's Theory of Relativity. It does not mean "guess" (the science word for "we think this might be true, but we don't really know" is "Hypothesis"). In particular, while you might expect it based on other uses of the words, in science laws are not necessarily "better" or "more true" than theories. In fact, Einstein's Theory of Relativity provides a better description of the motion of a mass being acted upon by a force than Newton's Third Law of Motion does. Kinetic theory is not a single statement or equation (therefore not a law), but it does a good job of describing and predicting certain properties of matter (therefore not a hypothesis), so it's best called a theory.