Create a free body (or force) diagram for a skydiver falling at a constant speed.

Should look like this.

Explanation:

The drag force must cancel the force of gravity.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.