# A couple specific Physics problem solving questions

1. Sep 23, 2010

### DrummingAtom

I'm in my first ever Physics class and have a few questions concerning skills involving solving Physics problems. I've been noticing that even though I get the right answers, my work getting there is a mess and unorganized. With that said, I have a hunch that won't fly in the upper level classes, which is why I'm trying to figure this out early.

When you're working on a problem do you try to stay away plugging in numbers too early? Like if a problem needs to have several things found to arrive at the final answer, do you make one large equation with only symbols *then* plug in numbers at the very end?

Also, when you get to the end of that a distinct relationship is found among the symbols. Is there anything from a creativity aspect that you do to gain more insight into the problem? I know this question seems a little strange, but I'm pretty new to Physics and want to develop some skills with solving problems as well as some creativity. Thanks.

2. Sep 23, 2010

### NobodySpecial

A few tips.
1, Draw a diagram - especially for any mechanics type problems
2, Don't put in the numbers until you have the equations rearranged/solved.
3, When you have the equations worked out, check that the units balance.
4, Although you shouldn't put in numbers too early you do need to have an estimate of the answer - or at least the magnitude of the answer. This is especialy important for astronomy/chemistry type questions with very large/small numbers. It's easy to be a factor a million out because you got a unit wrong or mistyped a calcuator button

3. Sep 23, 2010

### Redbelly98

Staff Emeritus
Yes, exactly.
Yes, at this point I check if the behavior of the equation agrees with what I know from common sense (or other knowledge I have). Just for example,
• As one variable is increased, does the result increase or decrease?
• As one variable is increased, does the result go through a maximum or minimum?
• What is the result when one variable is zero?
• What value of the variable would cause the result to be zero?
• What is the result when one variable approaches infinity?
• Do the units on both sides of the equation agree? Do the units of terms that are added or subtracted agree?
If the answers to those questions conflict with how I know things should be, that's a signal that I have made a mistake somewhere.