Is the answer 7? The number of degrees of freedom of a system can be viewed as the minimum number of coordinates required to specify a configuration. Applying this definition, we have:
- For a single particle in a plane two coordinates define its location so it has two degrees of freedom.
- A single particle in space requires three coordinates so it has three degrees of freedom.
- Two particles in space have a combined six degrees of freedom.
- If two particles in space are constrained to maintain a constant distance from each other, such as in the case of a diatomic molecule, then the six coordinates must satisfy a single constraint equation defined by the distance formula. This reduces the degrees of freedom of the system to five, because the distance formula can be used to solve for the remaining coordinate once the other five are specified.