Dimensional Analysis Help?

Question

I wanna have a good refresh because, Im taking physics and we're currently doing that.

Back in chemisty the teacher make the explanation so confusing I freak out everytime I see a dimensional analysis question now, even in physics with a nice teacher.

I get confused on what to do and what number to put next to the unit. Then when I do get things set, I have no clue how to multiply it to make it right because I confuse the numbers on top and bottom so yea. Also I don't get significant digits so well

I'd appreciated it if you'd help me and star this question.

Answer 1

were doing dimensional analysis too :]

http://chemistry.alanearhart.org/Tutoria...

Answer 2

Rather than rehash what I've already said, look here:

http://answers.yahoo.com/question/index;...

As for significant figures:

1) When adding or subtracting, use the smallest number of decimal places occurring in any of the values being added or subtracted.

2) When multiplying or dividing, use the smallest number of digits, regardless of where they are with respect to the decimal point.

3) To show that a zero to the left of the decimal point is not significant, underline the places that are.