Mathematically illiterate!

[Staiduk]

'Lo!

I find myself with a problem - I'm trying to figure out the weight of a given volume of water and none of my results make any sense. I'm totally hopeless when it comes to math - this has got to be the simplest of calculations but it's escaping me. I'll talk all day about history, arts etc. but throw a number in there and I'm toast. Ewww, I feel dumb sometimes.

Anyway; I have a cargo space for a fictional spacecraft 8 meters by 16 by 6. I figure the best way to establish how much cargo it could carry in weight would be to figure out how much that volume of water would weigh and use that as a maximum.

Ummm....help?

[cjl]

Well, water has a density of 1 gram per milliliter (cubic centimeter). There are 100 centimeters in a meter, so cube that to get 1 million cubic centimeters in a cubic meter. This means that for every cubic meter, you get 1 million grams, or 1000 kilograms of water (1 metric ton). In a container that is 8 by 16 by 6 meters, the volume is 768 cubic meters. This amount would hold 768 metric tons of water, or 768000 kg.

Does this help?

[Staiduk]

It does - that was one of the results I came up with; but it didn't seem to make sense. I knew water was heavy; but I didn't expect that heavy.

OK; thanks!

[randb]

1 cubic meter of anything is 1000L, and not 1L. Thats where some people get confused.

[01101001]

Mathematically illiterate

I've read several of the excellent Paulos' books that call it innumeracy.

Anyway, in these modern times, I let Google Calculator do the heavy lifting.

(8 m) * (16 m) * (6 m) * (1 (kg / l)) = 768 000 kilograms
(8 m) * (16 m) * (6 m) * (1 (g / ml)) = 768 000 kilograms
(8 m) * (16 m) * (6 m) * (1 (g / cc)) = 768 000 kilograms

That only requires that I remember the density of (standard pressure and temperature) water is 1 g/cc -- or one of the many equivalents -- and do a simple dimensional analysis as a confidence check: length*length*length*mass/volume is mass.

[Gillianren]

One of the standard tests in any psych eval is counting backward from 100 by 7s. I'm actually astonishingly good at this one, given that I'm very bad at most math.

[hhEb09'1]

1 cubic meter of anything is 1000L, and not 1L. Thats where some people get confused.

Or, at the other end, 1L is 10cm by 10cm by 10cm (4 inches by 4 inches by 4 inches), which if it is water does weigh 1 kilogram (2.2 pounds).

[randb]

Or, at the other end, 1L is 10cm by 10cm by 10cm (4 inches by 4 inches by 4 inches), which if it is water does weigh 1 kilogram (2.2 pounds).

I always thought that 1m^3 = 1L.

[TriangleMan]

I always thought that 1m^3 = 1L.

Nope. A cubic decimeter (i.e. 10cm x 10cm x 10cm) equals 1L. A m^3 is pretty big (larger than a cubic yard). Your average swimming pool is probably 30-40 m^3.

[gwiz]

I knew water was heavy; but I didn't expect that heavy.

Considerably denser than most space payloads. There's a lot of empty volume in most pieces of electronic kit. The only thing that comes close is propellant, and even then not many liquids are as dense as water.

[HenrikOlsen]

1 cubic meter of anything is 1000L, and not 1L. Thats where some people get confused.

No, 1 cubic meter of anything is 1000l, not 1000L

Or, at the other end, 1L is 10cm by 10cm by 10cm (4 inches by 4 inches by 4 inches), which if it is water does weigh 1 kilogram (2.2 pounds).

no, 1l is 10cm by 10cm by 10cm

I always thought that 1m^3 = 1L.

It might be, if you define the non existing unit L as 1000l

Nope. A cubic decimeter (i.e. 10cm x 10cm x 10cm) equals 1L. A m^3 is pretty big (larger than a cubic yard). Your average swimming pool is probably 30-40 m^3.

No, A cubic decimeter (i.e. 10cm x 10cm x 10cm) equals 1l, not 1L.

Grrrr, don't people realise that case matters in units?

[jas2000]

"Hello jas2000 it appears that you have not posted on our forums in several weeks, why not take a few moments to ask a question, help provide a solution or just engage in a conversation with another member in any one of our forums? "

Over here, we get to buy your milk in 1 liter packages.
Now, whereas milk has a lighter density than water, it will float on water, as long as you don´t open the package, in which case it will blend.

Come to think of it... I´m not sure about the density of milk... the fat in the milk should bring down the density, the calcium should push it up again - supposedly milk can have all kinds of densities, depending on this, and what species is involved.

[01101001]

I´m not sure about the density of milk... the fat in the milk should bring down the density, the calcium should push it up again - supposedly milk can have all kinds of densities, depending on this, and what species is involved.

Dairy Chemsitry and Physics: Density

With all of this in mind, the density of milk varies within the range of 1027 to 1033 kg m(-3) at 20° C.

It provides a table of dairy milk types and temperatures. Most all is just slightly denser than water except warm heavy cream.

[Bob]

So light cream is heavier than heavy cream. Who knew?

[randb]

No, 1 cubic meter of anything is 1000l, not 1000L


no, 1l is 10cm by 10cm by 10cm



It might be, if you define the non existing unit L as 1000l


No, A cubic decimeter (i.e. 10cm x 10cm x 10cm) equals 1l, not 1L.

Grrrr, don't people realise that case matters in units?

Wrong!!!! Both L and l are correct!!!

http://physics.nist.gov/cuu/Units/outside.html

[hhEb09'1]

It might be, if you define the non existing unit L as 1000l

The liter, or litre, isn't an official unit either.

No, A cubic decimeter (i.e. 10cm x 10cm x 10cm) equals 1l, not 1L.

Grrrr, don't people realise that case matters in units?

So does context

Regardless, I haven't been following the debate lately. I found this BIPM SI webpage that says the 16th CGPM resolved to allow both l and L as abbreviations for the litre, because of the confusion between 1 and l. At the time (1979), they allowed both l and L, and it looked like they were moving towards L. (A period is allowed after L there, because it is the end of the sentence.)

This US Metric Association Correct SI-metric usage webpage (last updated 2006-01-17) shows both l and L as acceptable abbreviations for liter.

[jas2000]

Milk heavier than water? Cool.
But at least butter will still float on water.
(like little ice-bergs... made of butter!!!)

[Halcyon Dayz]

In SI there is no such thing as kph.

Stop saying that!

^{(Well, maybe kilopascal/hour, the rate of change in pressure.)}

[Disinfo Agent]

Kilopascal/hour would be written kPa/h, or kPa h^(-1).

[TriangleMan]

Glad to hear that the devastating 'l' and 'L' controversey was sorted out by a crack team of international representatives at BIPM.

Actually I was taught in school that if you were using handwriting to use 'l' but that it had to be written cursively, instead of printed, to avoid confusion with 1. If typing then you used 'L'.

[trinitree88]

So light cream is heavier than heavy cream. Who knew?

Of course you knew. Those beautiful clouds that form in your ice coffee as you pour in the milk or cream over the ice cubes, and watch it drizzle, swirl, and make fabulous dreamy shapes as it finds it's way to the bottom...(though in the Southwest they barely drink the stuff). It has to be denser to do that.
BTW, it's how Spielberg created the approaching thunderstorm over LA in ET. They put a camera on the bottom of a swimming pool, and introduced milk into the far end (beyond critical angle)...then photographed those beautiful swirly, dreamy shapes, as the diffusion of the milk drifted towards the pool bottom. Don't know if it was digitally added or the cityscape was immersed in the pool...saw it on one of those movie-production TV shows.

[farmerjumperdon]

Glad to hear that the devastating 'l' and 'L' controversey was sorted out by a crack team of international representatives at BIPM.

The gallon is a much less controversial unit of measure.

[Halcyon Dayz]

The gallon is a much less controversial unit of measure.

At least there is only one litre.

From Wikipedia: Gallon

US liquid gallon is 231 in³ (exactly) or 128 fl oz (exactly) or 3.785411784 L
US dry gallon is 4.404 884 L
Imperial gallon is 4.54609 L (exactly)

[Disinfo Agent]

Glad to hear that the devastating 'l' and 'L' controversey was sorted out by a crack team of international representatives at BIPM.

Actually I was taught in school that if you were using handwriting to use 'l' but that it had to be written cursively, instead of printed, to avoid confusion with 1. If typing then you used 'L'.

In handwriting, you can use various kinds of visual aids to tell the l and the 1 apart. In printed text, you can always leave an empty space between the quantity and the unit, as you're supposed to.

[TriangleMan]

In printed text, you can always leave an empty space between the quantity and the unit, as you're supposed to.

Damn the Law! I'm going to leave the space out and stick it to "The Man"!

[Kristophe]

I'm going to sit this one out, and wait for the all important battle to the death over the proper spelling of metre/meter and liter/litre, which I'm sure that GrapesOfKilopi has initiated. I've already picked my side, but to maintain a tactical advantage I'm not yet announcing which.

[pmcolt]

Psst. Don't tell anyone, but... well, I would never do this, but a friend of mine occasionally uses u instead of µ to denote micro. It's just so much easier to type... erm, says my friend.

(And I was taught to use L rather than l, which looks nearly as awful to my eye as kph or KHz.)