Physics I Homework Standards
Problems are assigned twice weekly from the textbook or from
separate
notes. In order to adequately evaluate students' solutions to
homework in a timely fashion, certain standards are necessary.
If
these standards are not followed, the resulting problems may not be
graded and the student will lose credit for completing the homework.
1. The problem solution must be "selfcontained", i. e. the
nature of the problem must be indicated. It is best to explain
the problem in your own words.
2. The solution should be developed by invoking the primary
physical laws, writing the appropriate (easy to remember formula)
from
the physical laws involved.
3. The solution should be solved algebraically before any
numbers
are inserted. This saves a lot of work. It is much
easier
to write the symbol for density than to write the numbers, including
the powers of 10. It is much easier to manipulate the symbols
for
the quantities with the rules of algebra than to manipulate the
numbers.
4. Save "pluggingin" the numbers for the last step.
This
saves writing gobs of numbers and it minimizes errors.
5. Box or highlight the final answer, including the correct
units
propagated from the formula, and display the correct number of
significant digits.
6. The handwriting must be legible! The graders will not
waste time trying to decipher illegible scrawl.
Here is an example from a typical textbook:
2. A major motor company
displays
a
diecast model of its first automobile, made from 9.35 kg of
iron. To celebrate its hundredth year in business, a worker
will
recast the model in gold from the original dies. What mass
of
gold is needed to make the new model? The density of iron is
7.86
x 10^{3} kg/m^{3}, and that of gold is 19.3 x 10^{3}
kg/m^{3}.
Good solution:

The problem question has been
rewritten in own words.
The given information is clearly displayed with appropriate
symbols.
The formula based on fundamental definitions is clearly
displayed.
The technique for solving (notably that the volumes are
equal) is
clearly displayed.
The solution is first solved with the algebraic symbols in a
formula,
then the numbers are "pluggedin" to obtain the numerical
answer.
The numerical answer is displayed with the correct
significant digits
and units and the answer is boxed.
An interesting sideline is entered (not necessary, but it
shows some
realistic insight)! 
Bad solutions:
Besides the lack of showing the calculations or formulae used in the
solutions shown below, there are other faults.

Only the answer is displayed, the problem is not outlined in
sufficient
detail.
Incorrect regarding significant digits.
Answer not boxed or highlighted.


Formula not shown with algebraic symbols.
Units missing from the calculation.
Excess digits in the answer by copying all 11 calculator
digits!
This is the most egregious error! 

Error in the numbers as well as a power of 10. Student
should
realize
that the answer is ridiculous. The model made from
gold should be
considerably more massive than the iron model. 