I feel like such an idiot (Help please with unit conversions)

[APAlex]

Homework Statement

How am I supposed to know my unit conversions? like for example 1 pound is equal to 453.592 grams I don't know how people do it, it's like they have it all memorized in their head I can't think of a way for me to be able to memorize any of it or know it am I supposed to do something?

Homework Equations

The Attempt at a Solution

 

[Bystander]

they have it all memorized

Yes. Drill. Mind-numbing repetition of "the alphabet song." There are no pills --- that's still in the realm of sci-fi.

 

[berkeman]

Homework Statement

How am I supposed to know my unit conversions? like for example 1 pound is equal to 453.592 grams I don't know how people do it, it's like they have it all memorized in their head I can't think of a way for me to be able to memorize any of it or know it am I supposed to do something?

Homework Equations

The Attempt at a Solution

Welcome to the PF.

I have added some extra words to your thread title for you -- the title should reflect the question being asked in the thread.

As to your question, I know that a kilogram is about 2.2 pounds, but that's about as accurate as that conversion gets for me. I also know that an inch is 2.54cm, but I use that a lot in measuring things. There will just be some things that you do a lot where it's handy to memorize a few conversions (just like you will memorize some constants to a few decimal places, like pi, and c, and g, etc.). Where are you in your schooling right now?

 

[APAlex]

Dude I'm in college that's why I'm freaking out

 

[APAlex]

Is there anywhere I can look at all the conversions or such so I can memorize this

 

[Bystander]

Got a CRC Hndbk?

 

[berkeman]

Is there anywhere I can look at all the conversions or such so I can memorize this

Maybe wikipedia has a page on unit conversions... But just memorize the ones you will be using. It's a lot easier to memorize stuff that you use over and over...

 

[APAlex]

Thanks guys I'm going to go cry myself in a corner while I read these conversions over and over

 

[berkeman]

Yoiks, I just looked at the wikipedia page, and it definitely has *Way* too many units to go through. Did you know "bucket" is an official unit of volume...?

 

[Mark44]

Yoiks, I just looked at the wikipedia page, and it definitely has *Way* too many units to go through. Did you know "bucket" is an official unit of volume...?

And then there are furlongs per fortnight, and the number of electrons in a pint -- all kinds of cool conversions.

 

[APAlex]

Guys I need you to keep my brain from spilling.

 

[berkeman]

LOL

 

[GoodPost]

Well, I know that feeling when the given quantity is in kilometers per hour and the result is required in feet per second! Anyway, you should work conversion problems as much as you can to get familiar with the conversions techniques.

* Hmm ... by the way you have a scientific calculator, don't you? ; )


G.P.

 

[berkeman]

Well, I know that feeling when the given quantity is in kilometers per hour and the result is required in feet per second!

Just remember to use the trick to multiply by "1" for each unit conversion. Define your "1" so that you can cancel units to get to the final units you want.

For example, I want to convert 100km/hr into ft/s:

$$100\frac{km}{hr} * \frac{1hr}{3600s} * \frac{3280ft}{km} = 91\frac{ft}{s}$$

 

[GoodPost]

Just remember to use the trick to multiply by "1" for each unit conversion. Define your "1" so that you can cancel units to get to the final units you want.

For example, I want to convert 100km/hr into ft/s:

$$100\frac{km}{hr} * \frac{1hr}{3600s} * \frac{3280ft}{km} = 91\frac{ft}{s}$$

Wow great here we go, I normally do conversions in two steps but this looks pretty simple and straightforward.
Plus I'd like to add,
1 km = 1,000 m === (convert it into ft by the calculator ) 3280 !

Thanks,

G.P.