Converting metric to imperial (12in/1ft)^3

In summary, the author of the book got the equation for converting g to lbm wrong, but there is a program available online that can do the conversion for you.
  • #1
C3ss4
4
0
Hello. I am new to engineering and to imperial units, and currently learning by doing some exercises. I'm stuck on the following conversion:

  • 0.04 g / min x m^3 -> lbm / hr x ft^3
    I figured it like this:
  • 0.04 g / min x m^3 x (60min/1hr) x (1m/35,314)^3 x (1 lbm / 454g) =
    1,49x10^-4 lbm / ft^3 x hr

However, the author of the book gives the following solution:

  • 0.04 g / min x m^3 x (60min/1hr) x (12in/1ft)^3 x (1 lbm / 454g) =
    9.14 lbm / ft^3 x hr

It really lost me, why (12in/1ft)^3 its supposed to cancel out m^3? He does the same on a similar exercise converting cm^2 with (12in/1ft)^2.

Thanks for your time and help.
 
Engineering news on Phys.org
  • #2
Looks like the book has got it wrong.
Maybe there was a typo or OCR error where "in" became "m".

What book? what author? have you checked the web for an errata ?
 
  • #3
Not yet, but i will check. I was also thinking than the book might be wrong because really made no sense.

Thanks for your help :)
 
  • #4
Found new information:

Since 12in = 1ft, you can get a one by dividing both sides of the equation by 1ft, giving 12in / 1ft= 1. Because the result is 1, and the units can cancel out it makes sense after all.
 
Last edited:
  • #5
You were right the first time, the book has it wrong (yes, it does happen sometimes).
You can evaluate the equation directly using a program called calchemy. Here is it's "evaluation" of the equation:

0.04 g / min m^3 ? lbm / hr ft^3
(0.04 * gramm) / (minute * [meter^3]) ? poundm / (hour * [foot^3])
= 0.00014982723 lbm / hr ft^3

The program runs on iPhone, but there is a "web" version at:
http://www.testardi.com/rich/calchemy2/
that you can use for free, just cut and paste the equation above to give it a try (first line)
The second line shows the equation it "actually" evaluated (sort of "in longhand"), the third line is the answer.

Another web instance used to "work" at
http://www.calchemy.com
but that instance was broken by the service provider because of "security concerns" and has not been fixed... Still, there is a lot of good information about the program on the site.

The program carries units with the numbers, so you don't ever have to do any conversions "by hand". It takes a little getting used to, but once you get the hang of it you can calculate all kinds of things really easy. The syntax is "what you know, with units of measure" ? "units you want the result in"
It will even "solve" by dimensional analysis, it can do this because it knows what answer (units) you are looking for!
 
  • #6
My, that looks really useful for learning. I'll give it a try!

Thanks a lot: :)
 
  • #7
It is sort of working at http://www.calchemy.com
At least the answers are right, but the UI is still kind of messed up, the answer should be printed at the bottom, not in another page...
 

1. What is the conversion factor for converting metric to imperial (12in/1ft)^3?

The conversion factor for converting metric to imperial (12in/1ft)^3 is 1728. This means that 1 cubic foot is equal to 1728 cubic inches.

2. How do I convert cubic inches to cubic feet?

To convert cubic inches to cubic feet, you need to divide the number of cubic inches by 1728. This will give you the equivalent value in cubic feet.

3. Can I use (12in/1ft)^3 to convert any metric unit to imperial?

No, (12in/1ft)^3 is specifically used for converting volume measurements, not all metric units. For example, you would not use this conversion for length or weight measurements.

4. Is it necessary to convert from metric to imperial?

It depends on the situation. In some cases, it may be necessary to convert from metric to imperial, especially if you are working with a unit of measurement that is commonly used in one system but not the other. However, in many cases, conversions are not necessary and you can use whichever system is most convenient for you.

5. How accurate is the conversion from metric to imperial using (12in/1ft)^3?

The conversion from metric to imperial using (12in/1ft)^3 is accurate to the nearest thousandth. However, keep in mind that this is a standard conversion factor and may not be precise for all measurements, so it's always a good idea to double check your calculations.

Similar threads

Replies
6
Views
930
  • Introductory Physics Homework Help
Replies
6
Views
5K
  • Introductory Physics Homework Help
Replies
3
Views
3K
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Special and General Relativity
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
8K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
14
Views
4K
Back
Top