Question

How do you solve dimensional analysis questions? Where do you find the conversion factors?

Answer 1

Conversion factors can usually be found in your text book. The problems are solved by setting up a series of conversion factors to change the unit of what you are working with

Answer 2

do you have a particular problem we can do as an example?

Answer 3

5600 dm to m
my textbook has a table of the SI prefixes

Answer 4

I'm not sure how to use the numbers in the table to solve the problems

Answer 5

this is the table:
https://stpatschem11.files.wordpress.com/2009/09/600px-prefixes.png

Answer 6

So the prefixes can be applied to any unit of measurement, for this example you are working with meters. The chart says that 1 deci meter is equal to 10^-1 meters or .1

There are two ways to do this, one is simply by moving the number of decimal places, the second is setting up a dimensional analysis chart

\[5600dm*\frac{ 10^{-1}m }{ 1dm }\]

Answer 7

multiply across and divide, the dm cancels and you are left with your answer in the unit of meters

Answer 8

isn't the denominator supposed to be 10^-1?

Answer 9

Bleh, I'm sorry. I'm confusing my self lol. A decimeter is smaller than a meter, it is 1/10th the size of a meter, thats why .1 meters is equal to 1 decimeter.

Answer 10

so yes, flip them :D

Answer 11

i checked on the calculatoe and the correct answer is 560 meters

Answer 12

AHhhhh ....yes because we were going from dm to meters. I had checked it the opposite direction. Either way, do you at least understand the concept now?

Answer 13

so whats the final set up?

Answer 14

im still a little confused

Answer 15

For this problem it is how I wrote it in the previous comment. In general you have to first determine your conversion factor and then set it up how I showed you before so that the units cancel

Answer 16

ohh so your first set up is correct?

Answer 17

yes, sorry for the confusion. You set up the problem so that the units will cancel, then multiply across and divide my the bottom (in this case bottom is 1 so it does not matter). See how if you multiply 5600 by .1 you will get the correct number, the dm cancels and you are left with 560 m

Answer 18

And the prefixes will work with all units, so it does not have to be meters. You can go from decigrams to grams or deciliters to liters and vice versa

Answer 19

thank you so much! you were really helpful!

Answer 20

No problem. Thank you.