Anyone good at dimensional analysis...I need some help

[DustyWust87]

I suck at this stuff, im usually not a dumb kid but I just cant get this stuff

Heres what I need help with:

1.) Convert 10 grams / Liter into milligrams / Liter.


2.) Convert 151 Meteres / Second into meteres / minutes.

3.) Convert 120 kilometers / hour into meters / second.

4.) Convert 1.2 x 10^5 grams / L ubti kilograms / ml.


I have like 35 problems that have to be done by tonite (been putting off these worksheets, why i signed up for advanced chemistry i will never know)

I know these are probably simple and im an idiot etc etc...but any help would be appreciated

 

[dullard]

Just remember two things:
A) you can multiply units, and
B) If you multiply something by 1, then you don't alter it.

So your goal should be to multiply all of your original equations by the number 1 formed by the current and desired units. I know that sentence is confusing so lets step you through your problems.

1) Convert 10 gram / liter into milligram / liter.
You should know that 1000 milligram = 1 gram, thus 1000 milligram / 1 grams = 1. Now multiply your original value by 1:
(10 grams / liter ) * (1000 milligram / 1 gram)
Note how the unit 'gram' appears in the numerator and denominator. Thus you can cancel it. If you don't see that, then lets rearrange the equation a bit:
(10 gram / 1 gram) * (1000 milligram / liter)
See how the unit 'gram' appears in both the numerator and denominator? They cancel out. So you are left with:
10 * 1000 milligram / liter = 10000 milligram / liter.

2.) Convert 151 Meteres / Second into meteres / minutes.
You should know that 60 seconds = 1 minute. Thus 60 second / 1 minute = 1. Multiply your original value by 1:
(151 Meteres / Second) * (60 seconds / 1 minute) = 151*60 meters / minute = 9060 meters / minute

 

[maziwanka]

for example, you want to:

x g/L -> mg/L so you have to do: x g/L * 1000 mg/g = 1000 * x mg/L (since the grams in the numerator of g/L cancel the grams in the denominator of mg/g).

x m/s * 60 s/min = 60 * x m/min

x km/hr * 1000 m/km * 1/3600 hr/s = 1000/3600 * x m/s

x g/L * 1/1000 kg/g * 1/1000 L/mL = 1/1000000 * x kg/mL

hope this helps.

+ronnie

 

[bunker]

1.Text
2.Text

 

[Viper GTS]

There are lots of pages out there with info on how to do this, it is IMPORTANT that you understand how to use it.

It's also called the Factor-label method and the Factor-unit method.

here's one

Once you "get it" you'll never forget it & it will make perfect sense. Don't give up until you understand it.

Viper GTS

 

[dighn]

dimensional analysis heh. i thought it was some kind of higher level math

 

[dquan97]

It takes a bit of getting used to...I remember having a terrible time with it during HS 10th grade in AP Chemistry. Once you get it, it will make sense

 

[rgwalt]

When you get more comfortable with dimensional analysis you will be able to show that the cooking time for a turkey scales as mass to the 2/3 power. Woohoo!

R

 

[MisterYu]

I use a program called convert.exe (download at link below) all the time. I has practically everything.

Very handy, especially when I'm doing work in closed area at work and there's no internet access allowed.

Link

This is just a tool, it'll give answers without showing all the work.

 

[deftron]

I thought you were going to need help solving a Rubik's Cube.