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# Some help with a math/physics/general science question?

universum

User ID: 23683626
09/14/2012 03:08 AM
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Some help with a math/physics/general science question?
A friend of mine has a small assignment due for school in the morning and she can't figure it out. I think I've found it, but there's a good chance I'm totally wrong. Here's the layout of the question:

There is calcium in sea-water that the aim is to refine.
Assume the density of sea-water itself is 1.025g/mL.
In 1kg of sea-water there is 0.4g of calcium.

In "m^3" how much water must be processed to get 10^3 tons of calcium? A ton is 2000lbs and 10^3 = 1000, so 2000 x 1000 = 2000000lbs. A pound is 453.592g so 2million of them is 907184000g <---that's the target calcium to refine--|

So in meters cubed, what amount of sea-water must be refined?

I hope there is someone bored and up to the task, this question really beat her up. I think it's much simpler than she's making it.

Last Edited by universum on 09/14/2012 03:11 AM
Anonymous Coward
User ID: 23543603
United States
09/14/2012 03:17 AM
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Re: Some help with a math/physics/general science question?
A friend of mine has a small assignment due for school in the morning and she can't figure it out. I think I've found it, but there's a good chance I'm totally wrong. Here's the layout of the question:

There is calcium in sea-water that the aim is to refine.
Assume the density of sea-water itself is 1.025g/mL.
In 1kg of sea-water there is 0.4g of calcium.

In "m^3" how much water must be processed to get 10^3 tons of calcium? A ton is 2000lbs and 10^3 = 1000, so 2000 x 1000 = 2000000lbs. A pound is 453.592g so 2million of them is 907184000g <---that's the target calcium to refine--|

So in meters cubed, what amount of sea-water must be refined?

I hope there is someone bored and up to the task, this question really beat her up. I think it's much simpler than she's making it.
Quoting: universum

All conversions, shouldn't be that hard. I'll type something up in a moment.
Anonymous Cowherder
Stop the Inanity!

User ID: 2245483
United States
09/14/2012 03:18 AM

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Re: Some help with a math/physics/general science question?

so about 400g of calcium per 1m^3.

so I'd say somewhere around 2268960 m^3.

I could be off though, it's late.
Repeal the 17th Amendment and the Reapportionment Act of 1929!

Restore the Republic.

It's a flower, not something to be feared.

- Moo!
Anonymous Coward
User ID: 23754928
Australia
09/14/2012 03:21 AM
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Re: Some help with a math/physics/general science question?
See if you can get her to try harder.
Anonymous Coward
User ID: 23754928
Australia
09/14/2012 03:23 AM
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Re: Some help with a math/physics/general science question?

so about 400g of calcium per 1m^3.

so I'd say somewhere around 2268960 m^3.

I could be off though, it's late.
Quoting: Anonymous Cowherder

"Assume the density of sea-water itself is 1.025g/mL.
In 1kg of sea-water there is 0.4g of calcium."

"Give a girl a fish and you will feed her for a day. Teach her how to fish..."
universum (OP)

User ID: 23683626
09/14/2012 03:24 AM
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Re: Some help with a math/physics/general science question?

so about 400g of calcium per 1m^3.

so I'd say somewhere around 2268960 m^3.

I could be off though, it's late.
Quoting: Anonymous Cowherder

Thanks for the attempt, but it's "sea-water" (density of 1.025g/mL whereas regular H20 is a 1mL-to-1g-to-1cm^3 ratio.) so there has be more to the calculation.

Last Edited by universum on 09/14/2012 03:26 AM
Anonymous Coward
User ID: 23543603
United States
09/14/2012 03:29 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Anonymous Coward
User ID: 23543603
United States
09/14/2012 03:30 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

I think that's right, it's late though. But it makes sense to me.
Anonymous Coward
User ID: 23754928
Australia
09/14/2012 03:31 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

Please provide the working you used to the allow that number of significant figures in your answer.

Thanks.
Anonymous Cowherder
Stop the Inanity!

User ID: 2245483
United States
09/14/2012 03:32 AM

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Re: Some help with a math/physics/general science question?

so about 400g of calcium per 1m^3.

so I'd say somewhere around 2268960 m^3.

I could be off though, it's late.
Quoting: Anonymous Cowherder

Thanks for the attempt, but it's "sea-water" (density of 1.025g/mL whereas regular H20 is a 1mL-to-1g-to-1cm^3 ratio.) so there has be more to the calculation.
Quoting: universum

yup, I realized I used fresh water....

Repeal the 17th Amendment and the Reapportionment Act of 1929!

Restore the Republic.

It's a flower, not something to be feared.

- Moo!
Anonymous Coward
User ID: 23543603
United States
09/14/2012 03:34 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

Please provide the working you used to the allow that number of significant figures in your answer.

Thanks.
Quoting: Anonymous Coward 23754928

Ok 1kg of water we are told gives is .4g of calcium.
We need 1,000tons of of calcium.
The OP did the work getting the amount of calcium needed.
Then I just did the conversions, I hope I didn't skip a step.
universum (OP)

User ID: 23683626
09/14/2012 03:35 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

Thanks, that's what I got as well but she kept saying it didn't work out right. I think she'll see it in the morning, now that I'm more assured we have the solution.
Anonymous Coward
User ID: 21958800
United States
09/14/2012 03:35 AM
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Re: Some help with a math/physics/general science question?
2,267,960 cubic meters of water at 400 grams per cubic meter
Anonymous Coward
User ID: 23543603
United States
09/14/2012 03:38 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

Thanks, that's what I got as well but she kept saying it didn't work out right. I think she'll see it in the morning, now that I'm more assured we have the solution.
Quoting: universum

Ok I just triple checked everything. There's a lot of conversions, a LOT, but I did the math both ways, 2,212,643.90243 (repeating) m^3 is the answer. That's a lot of sea water!
universum (OP)

User ID: 23683626
09/14/2012 03:47 AM
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Re: Some help with a math/physics/general science question?
907,184,000g / .4 = 2,267,960,000 kg's of sea water needed.

1.025g/ml (kg/1000g)(ml/cm^3)(100^3cm^c/m^3)= 1025 kg/m^3

1025kg per cubic meter.

2,267,960,000 / 1025 = 2212643.90243 m^3 processed to refine the required 10^3 tons of calcium.
Quoting: Anonymous Coward 23543603

Thanks, that's what I got as well but she kept saying it didn't work out right. I think she'll see it in the morning, now that I'm more assured we have the solution.
Quoting: universum

..only I arrived there two different ways, I can't remember the first but I figured that 1kg of sea-water was equal to 975.6097561mL so therefor 0.4g of calcium in 975.6097561mL.

907184000g / 0.4g = 2267960000

so 2267960000 x 975.6097561mL = the number of mL needed. I converted to cm^3 and then to m^3, then arrived at what google also agrees with, by saying: "2 267 960 000 x 975.6097561 mL = 2 212 643.9 m^3" when I query "2267960000 x 975.6097561mL"

Last Edited by universum on 09/14/2012 03:52 AM