Group Problem Solving Strategy

Model

  • Classify the problem according to the general physics principles, models, and equations that apply. (e.g. Newton's second law, conservation of energy).
  • Writing down reasonable assumptions and estimations needed to solve the problem.
  • Guesstimate a reasonable range for the answer based on your own common-sense experiences, geometry, or simple calculations.
  • Consider how the answer should vary for limiting cases of the initial conditions. (e.g. What happens when an angle approaches 0 or 90 degrees or when a mass goes to zero?)
  • Look for key phrases like "at rest," or "falls freely" for clues about relevant physics principles.

Visualize

  • Draw a motion diagram to help visualize the situation (not needed for object at rest).
  • Do a complete pictorial diagram including
    • Coordinate system (with position, velocity, time, and acceleration marked if object is moving)
    • What the question is asking for
    • Writing down the relevant known and unknown quantities with units.
  • Draw any additional diagrams or graphs needed to visualize the physics of what's going on.
  • Go back and forth between these representations as needed.

Solve

  • Write down relevant general equations (express models and general physics principles in equation form).
    Make sure that you have enough equations to solve the problem (the same number of independent equations as variables).
  • Describe step by step how you will use these equations to solve the problem.
  • Solve for the desired unknown variable (on the left of the equation) in terms of the known variables (on the right). This may require manipulating and combining several equations without substituting numbers.
  • Substitute known values, calculate a numerical answer, and round the answer to the appropriate number of significant figures based on the precision of the input data.

Assess

  • Check your answer. Is result believable?
    • Does the answer agree with the prediction in the Model step?
    • Are the units correct?
    • Does the result have the correct sign or direction?
    • Does the algebraic result make sense for limiting cases as predicted in the Model step?
  • Why was this particular problem assigned?
    • What is the key point or critical issue in this problem?
    • What did you learn from doing this problem?
    • How is this problem similar or different from other problems you have examined?