Forbidden words and phrases for Physics problem solutions
These phrases do not add anything to a solution, and should be
avoided.
"We know that..." How
do you know?
"By symmetry..." Always discuss exactly which symmetries
exist, and how they affect your analysis!
"Clearly.." If it is really clear, this word is superfluous.
"It is obvious that..." Same as above.
"This is easily done." See above.
"it" Usually ambiguous: use the appropriate noun.
"this" "that" Same as above
"From Tables.." Not in Physics 785/485! In classes where
tables are allowed, always give the precise reference (title of table,
formula number,
page number etc.)
"just" almost always leads to problems.
"My result shows me that..." How does it show you?
"This can be used to show that..." variant of above
"We can say that.." Just say it!
"We can write.." Just write it!
"Note that.." Often used instead of a properly reasoned
argument.
"From Mathematica." If you use software like this always show the
input to the program and its output. Be aware that Mathematica
makes errors! Always CHECK the results.
Frequently mis-used symbols and
phrases:
-----> When used correctly, this
symbol means "tends to" or "becomes".
Double arrow ("implies" symbol). If you cannot substitute the
word "implies", you are misusing the symbol. It should
never appear pointing downward, upward, or any direction other than to
the right.
The "infinity" symbol may ONLY appear after the arrow ------>.
It must never appear after an equals sign, after a mathematical
operator such as +, - or ×, or in the numerator or denominator of
a fraction.
The symbol 0 (zero) may never appear in the denominator of a
fraction. If you are trying to do this, you probably need to take
a limit.
"By definition.." or " ... is defined as...". Always
CHECK the definition before you make this assertion. 9 times out
of 10 when students say this it is not true.
An equals sign needs something on both sides of it, not just one.
Mathematical operators may not be placed in sequence: for example "2 +
- 3" is not legal. You may need to use parentheses: "2
+(-3)" is fine.