Problem Statement

Sample solution

Annotated sample solution

Notes:

1. Including a brief statement of the problem makes grading easier and makes the solutions more useful for later study, such as preparation for a licensing exam.

2. Labelling is extremely important to show the logical flow an underlying reasoning in your solution, and for later study.

3. Most equations are based on a diagram. It is important to have a very clear diagram to show the basis for the equations. Most errors result from a lack of clarity in the diagram rather than miscues in the manipulation of the equations.

4. Without units, numbers lose their physical meaning, and so are important to maintain contact with that meaning. Also, errors commonly result from mismanagement of units.

5. Without clear sign conventions, it is very difficult to check equations. Always include clear sign conventions.

6. Clearly indicate final answers, since it it often hard to tell otherwise. Drawing a box around the final answer is a good graphic convention. Drawing all forces in the correct sense makes it possible to step back and get a feel for the force balance of the situation, an important step in catching errors and in developing an intutuitive feel for force balance.