Physics - Problem Solving Steps

To solve a physics problem, it is often useful to follow a common set of steps. You may not necessarily use all of these steps for a specific problem, and you may sometimes follow a different order of steps

1. Read the problem. You should try to understand the problem and convert the problem statement into a short statement or set of points to describe the problem more succinctly. Include statements about conceptual processes, e.g. kinematics problem, conservation of energy, or conservation of momentum.
2. Draw a diagram. All dynamics problems (those with forces) must have a free-body diagram.
3. State the known and unknown variables. From the problem statement write down the variables with their values and units. Determine the unknown(s). Perform unit conversions on your known quantities, if necessary. Check that all values have units from one system only. (This is usually but not always the S.I. system)
4. State the equations (formulae). Determine the equations that relate to the problem. There may be more than one way to solve the problem so group the equations by the type of possible solution.
5. Solve the equation(s). Solve algebraically for the unknown(s).
6. Substitute known values into the solved equation. Include values and units.
7. Calculate unknown from known values. State final value in appropriate format (fixed, scientific, or engineering). Use the correct number of significant figures. Convert final units if necessary.
8. Check final answer for reasonability. Does the answer make sense? E.g. Is a
   velocity greater than the speed of light? Is a mass more than the total mass of the universe? Do you have someone lifting a mass that is greater than the mass of their car?
9. Substitute answer into alternate formulae. Check the consistency of the final result by substituting values into the formulae from an alternate solution and make sure the solution is the same.
10. Write a concluding statement. Be sure that your final answer has the correct number of sigfigs and the correct units. Be sure that all vectors have both magnitude and direction. Be sure that you have answered the original question.