Problem Solving Strategy
- Focus: Translate the words of the
problem statement into a visual representation:
- Sketch the situation,
noting on the sketch the important quantities, known and unknown.
- Identify the specific
question(s) that must be answered.
- Identify the general
approach you will use, the physical principles involved.
- Identify any
assumptions that you will have to make.
- Identify the known and
unknown quantities and the constraints.
the problem into the terms and tools of physics.
- Construct idealized
diagrams with labeled coordinate systems for each quantity of interest.
- Assign symbolic names
to the relevant known and unknown quantities.
- Assemble the relevant
fundamental equations that relate the known and unknown quantities (some
you may not end up using.)
- Identify your Target
- Mathematics: Translate the physical description
into a series of mathematical actions.
- Numberless Algebra
(plugging numbers in too early obscures your reasoning and hides mistakes)
with an equation that includes the target variable.
there is another unknown in addition to the target variable, identify another
equation that includes this variable.
Solve the new equation for this unknown and substitute this solution
into the previous equation.
this process until the only unknown quantity is your target.
the resulting equation for the target quantity.
- Substitute the numeric
values (along with their units) into the final equation and compute the
numeric solution. Simplify
the units (ex. m/(m2*Hz) = 1/(m*Hz) = 1/(m*1/s) = s/m.)
- Check and Evaluation: Algebra errors are as easy to
detect as they are to make.
completeness: Did you answer
all the questions posed by the problem?
- Check units: The units should be appropriate
for the target quantity (ex. if you solved for a speed, but got the units
of m/s3 instead of m/s, something went wrong.)
- Evaluate answer: Are the sign and magnitude of the
answer reasonable (ex. if you find that the speed of sound is 3,344 m/s
when the air temperature is 40°C, something went wrong.)