Problem Solving Strategy

In a general physics course a student is asked to solve many problems. It is generally assumed that solving problems is the best way to clarify the concepts and principles of physics. This is true, provided that a student is able to make solving problems a real learning experience. It is possible that solving problems becomes only a routine: "How to discover the right equation." If a student approaches problem solving with the attitude that she/he only has to find the equation that will give the right answer, much time may be spent, but little learning of physics will take place. To make problem solving a more rewarding and profitable part of general physics, the following procedure should be kept in mind constantly.

1. Read the problem carefully enough so that you can state in your own words what physical situation is being described.
2. Draw a diagram or simple picture of the physical situation as you reread the problem. This is essential to the understanding of most problems. Trying to solve a problem mentally or intuitively usually consumes much time with no results.
3. Label all physical quantities in the diagram using appropriate letters and choose a coordinate system.
4. Identify the physical principle(s) or law(s) you think you ought to apply to the problem, as well as the knowns and unknown. List them all and circle the unknowns.
5. Equations are written down next which relate the physical quantites (knowns and unknowns) and which are consistent with the pricinple(s) or laws(s) from the previous step.
6. Solve the set of equations algebraically for the unknown quantities. Do not substitute in known values (unless they are zero) yet – some cancellation may take place that will simplify your calculator operations in the next step.
7. Substitute in the known values with their units to find numerical values with units for the unknowns.
8. Check your answer: Are the units correct? Is the number (including sign) reasonable?