metric made easy

[Hank49]

1 litre of beer == 10 euros ?! ouch. Glad we dont have the daft political symbol that is the euro here Oh, i still drink in pints

Another very useful metric thing for calculations is roughly 10m of water is equivalent to 1 atmosphere pressure (ie 1 bar).

Exactly. One BAR is one kg/ square centimeter. Or, 10 meters of water in a 1 cm square tube. (1 liter, or 1 kg)

 

[Firebrand]

After exhausting myself searching on the internet, I've come to the conclusion that hank is right. Sorry Mark.

 

[pete340]

Why do I think Hank's right, even if it seems wrong when I try to visualize it?

1 milliliter (ml) = 1 cubic centimeter (cc), and a liter includes 1000 ml (by definition); so a column of water 1 cm on a side would have to be 1000 cm (or 10 meters) tall. But when I imagine that column of water - and I think I am remembering correctly that it takes 2.54 cm per inch - I find it hard to imagine that column of water reaching so high from just one liter. But I also can't imagine it reaching only one meter, for whatever that's worth. My brain hurts.

But you're using the metric system. Isn't that supposed to make everything easy?

 

[Jamdiver]

1 meter = 3.3 feet.
210 bar = 3000 psi. Actually 207 bar, but you get my drift.
1 psi = 0.06895 bar

 

[Charlie99]

here is the simplicity and geometric beauty of the metric system:

Let's look at this simplicity in more detail ......

one liter of water weighs one kilogram

Approximately. Not by definition. Exactly true only at specific temperature pressure combinations.

one liter of water if squeezed onto a square centimeter will make a water column 1 meter high.

No. It will be 10 meters high. Yep. Metric is easy. .

the pressure at the bottom of the 1 meter water column with be 0.1 of an atmosphere.

Nope. It will be 0.1bar though. (Bar isn't an SI unit. Pascals are SI. a bar is 100,000 Pascals or 0.1 megaPascal. A standard atmosphere is 101.325kPa) So you should be asking for a 20 megaPascal fill

to heat the water 1 degree celsius, you will need 100 calories.

either 1 calorie or 1000 calories, depending upon what definition, is what you need to raise 1 kg of water 1 degree C.

see, easy huh? beautifully illustrated....

Yep. Easy.

 

[hdtran]

this originated from a thread that got hijacked today regard passports or something, but for those that are metrically impaired, here is the simplicity and geometric beauty of the metric system:

one liter of water weighs one kilogram

one liter of water if squeezed onto a square centimeter will make a water column 1 meter high.

the pressure at the bottom of the 1 meter water column with be 0.1 of an atmosphere.

to heat the water 1 degree celsius, you will need 100 calories.

a cubic meter of water will weigh one metric ton.

and one liter of beer will cost ten euros.



see, easy huh? beautifully illustrated....

1 cm x 1 cm x 1000 cm = 10^(3) cm^3 = 1 L, so the folks saying 10 m are correct, and Cancun Mark is incorrect here.

To heat 1 L of water by 1 deg C takes 1000 calories, not 100. The preferred unit here, unfortunately, is not the calorie, but the joule. To add to the confusion, the "food" calorie is actually a kilocalorie. To differentiate food calorie (kcal), it is sometimes written Calorie (rather than calorie, e.g. 1 Calorie = 1 kcal).

A 10 m column of water (or approx. 30 ft) in 1 g gravity has an additional pressure of 1 atm (approx. 10 N/cm^2, or 10x10^4 N/m^2, or 100 kPa). If NASA's contractors had actually built the Mars probe rockets to the NASA specs (SI, or International System units) rather than customary US english, it would probably not have crashed...

10 E(funny symbol) for 1 L of beer is pretty steep. I'd expect to pay 2 or 3 E(funny symbol) for 0.5 L. But my preferred tipple is wine...

Strictly speaking, 1 cubic meter volume of water does not weigh (or mass, more correctly speaking) one ton. It will be a bit less, depending on temperature (or more, depending on salinity )

Cheers!

 

[Hank49]

either 1 calorie or 1000 calories, depending upon what definition, is what you need to raise 1 kg of water 1 degree C.

Yep. Easy.

A calorie is the amount of heat (energy?) required to raise 1 cc of water 1 degree centigrade. I think. So yes, 1000 calories would be required to raise a liter of water that much. Or a beer? Which is what this whole thing started about. Hey Mark, sorry for drifiting of topic.

 

[RickSp]

You may want to specify that you are referring to fresh water. Seawater density about 1.0250 gr/cm3 whereas fresh water is 1.000 gr/cm3.

As an old salt, it does make a difference.

Rick

 

[Peo]

To heat 1 L of water by 1 deg C takes 1000 calories, not 100. The preferred unit here, unfortunately, is not the calorie, but the joule. To add to the confusion, the "food" calorie is actually a kilocalorie. To differentiate food calorie (kcal), it is sometimes written Calorie (rather than calorie, e.g. 1 Calorie = 1 kcal).

And the 'food calorie', as you said correctly abbreviated kcal is actually a kilo-calorie, that's the k in kcal. Unfortunately the chef didn't know that and thought a kilo was a kilo-gram, so he said calorie.

 

[Charlie99]

1 meter = 3.3 feet.
210 bar = 3000 psi. Actually 207 bar, but you get my drift.
1 psi = 0.06895 bar

An easy way to convert from meter to feet or vice versa is to
first "go the wrong way" by a factor of 3; then change the decimal point.

For example, 24 meters divided by 3 is 8. Add a zero to get 80'.
100 feet x 3 is 300. Drop a zero to get 30 meters.

---------------

Going from a psi-marked SPG to bar is easy if you just remember 70 bar per 1000 psi; 35 bar for 500psi.

When diving AL80 with an SPG in bar, I just remember 200 bar is more or less a full tank, 100 bar is half a tank. If I need psi number, I just add 50% and drop a zero (divers really only measure in hundreds of psi).

After going through conversions a couple times for a very confused UK guy diving with imperial rental gear in Key Largo, we finally got to the real heart of the matter ...... when the spg gets to the yellow we should head back, when it hits the red, we should be at safety stop or on the boat.

If I were doing Discover Scuba tours, I'd be strongly tempted to replace the faceplate of the SPGs with a simple car fuel gauge type of labeling ....... full / half / one-quarter / Empty!