But there are some questions that come to mind: Calculus students typically meet this problem somewhere in the second semester.

It is one of the simplest examples of a differential equation.

Suppose, in repaving your driveway, you find a stash of old coins buried in the ground. Of course there are more outlandish explanations, like somebody counterfeiting 1920 coins in 1900 (and successfully anticipating any changes in design in the meantime), or secretly tearing up part of the driveway after 1950, but unless someone comes up with really persuasive evidence, we're justified in ignoring these hypotheses.

The driveway was poured in 1950, and the coins are all dated 1920. Radiometric dating generally requires that a system be closed - in other words, has not had material added or removed.

Uranium-lead dating methods often use this approach because some of the minerals used in dating lose the lead decay products over time.

It's amazing how often people fail to realize that you can't date materials if they don't have the necessary ingredients. You can't use carbon-14 to date an arrowhead with no carbon in it.

What radioactive materials actually do is decay according to a law: Decays/Time = K * Number of atoms K is a constant called the decay constant.

Let t stand for time and N(t) stand for the number of atoms at time t .

In calculus terms, we write: d N(t)/dt = -K * N(t) or d N(t)/N(t) = -K dt The minus sign means that each decay decreases the total number of atoms.

Integrating both sides, we get: ln N(t) = -Kt C C is the constant of integration that we can often ignore, but not here.

Carbon-14 dating is often used for historical objects and young prehistoric objects, but it's based on the fact that all living things start out with a known amount of carbon-14. If the arrowhead is stuck in a bone, you can date the bone.

The most common dating methods for rocks are based on radioactive isotopes of potassium, rubidium, uranium, and thorium.

Furthermore, Parentium and Daughterium are so different in chemical properties that they don't otherwise occur together.