Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: AngelShare on August 04, 2005, 04:27:58 PM
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I'm taking a summer course for Chemistry but I'm still terribly lost. I read Chapter one of my book (Yes, I'm very very far behind. I took Algebra as well and since I can do that on my own we've been looking for help with Chemistry to no avail...Algebra is going great but I have to put it down to start Chemistry now, oh God.) I've got most of this lesson done but I can't figure some of it out for the life of me...book, useless.
1. How do conversions involving volumes (ft.^3 to m.^3) differ from standard conversions (ft. to m.)?
I didn't think there was any difference but then again, I'm not great at conversions...I thought the only difference was just the way they were labeled...volume is ft.^3 while standard conversions are just ft.
2. International Mail Carriers, an overnight delivery service, charges $1.00 per cubic centimeter (cm.^3). How much will it cost to send a package that is 13 cm wide, 8 cm long, and 2 cm deep?
I need the equation but I'm not sure of where to start. I, again, looked in the book but apparently I'm missing something in the four page long first chapter. *Pushs her book aside* Do I multiply 13, 8, and 2 together to get the price?
3. Explain why the metric system if a necessary tool for scientists. How do they use it? Include three advantages.
I know the advantages, those were clearly pointed out in the book but why it's necessary, what they use it for wasn't pointed out clearly enough to write a whole 7-12 sentence essay. Even pointing me to a good, helpful site would do as I'm not looking for someone to do these for me. I'm just really lost when it comes to this stuff, even the basics confuse me...I had a tutor try and an hour long session later, we had only gotten one page done. :-[ :'(
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1) now we're working in 3 dimensions, so for example when we increase 10 times, then 3 dimensions goes 10 times, so the conversion factor is not 10 but got 1000. So every step is not a factor 10 but a factor 1000.
2) calculate the volume with V = A * h. since 1 cm^3 costs 1$ you can use a table/cross multiplying to get the price.
3) if you want to communicate all over the world, it's easy to speak the same language --> the metric system. Also it's easier ( powers of ten --> kilo, deca, centi and so on)
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1) now we're working in 3 dimensions, so for example when we increase 10 times, then 3 dimensions goes 10 times, so the conversion factor is not 10 but got 1000. So every step is not a factor 10 but a factor 1000.
So, the difference is when working with volume you're working with 3 dimensions but standard conversions, you aren't?
2) calculate the volume with V = A * h. since 1 cm^3 costs 1$ you can use a table/cross multiplying to get the price.
I'm afraid I don't understand...V=Ah? A being area? A= L(w)? Cross multiplying? ???
3) if you want to communicate all over the world, it's easy to speak the same language --> the metric system. Also it's easier ( powers of ten --> kilo, deca, centi and so on)
Yeah, that was a part of the three advantages but I don't know what scientists use it for.
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1) correct
2) Indeed A = area and volume is given by V = A * h ( remember volume has three dimensions)
if you make a table in this form:
a | b
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c | d
Then b/a = d/c and thus a * d = b * c ( constant factor) and looking at the table, a cross is formed. That's why it's called cross multiplying.
Now it's easy to fill in the table like this:
1 cm^3 | 1$
208 cm^3 | x$
because of the above: 1 * x = 208 * 1 now x can be solved: 208 $
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hi
2. the general volume eqution for a box is heigth x width x deepth, og simplyfied areal x heigth.
3. as a native metric-system-user, i have a hard time doing math with the imperial system...
13' 5" x 24' 3", how do you calculate this quick? convert to inch, times, and convert back or? :) does you calc's support imperial units, if not here is another good reason for using metric system in sience...
do you have any unit for very small length? like nanometers etc.
i think this is some okay arguments
sorry for my bad english, it's just my second language :P
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arent some of these measurement units are actually modified metric units?
eg. 1 angstrom = 10-10m
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even better. :)
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Light years is an other example. Way more convenient for astronomers to talk in light years than 10^17meters
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Okay, so far I got number one but numbers two and three still aren't clear. Number two still has me lost as the explanation I was given (Cross mutliplying and such.) wasn't in the book...*Rubs temples* Four pages for chapter one is not enough... >:( :D
As for three, I still don't know what they'd use the metric system for...
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Light years is an other example. Way more convenient for astronomers to talk in light years than 10^17meters
9.46*1015
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Light years? I'm still on what do scientists use the metric system for? :D
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Do I multiply 13, 8, and 2 together to get the price?
Exactly. You have to calculate volume of cuboid. Doesn't matter what units its asize are in - be it cm, the answer will be in cubic centimeters, be it inches - the answer will be in cubic inches. Then you should multiply the volume by the charge for 1 cc, which happens to be 1.
As for three, I still don't know what they'd use the metric system for...
This is stupid question, that's why you have problems answering it. Metric system is not a must for anyone. However, it makes life much easier. Using metric system you don't have to convert inches to feets, feets to yards and yards to miles, and the conversion between length units means only moving decimal point. It is only a matter of efficiency.
If you want to make your life heavier, you can even use Roman numerals instead of Arabic ;D
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This is stupid question, that's why you have problems answering it. Metric system is not a must for anyone. However, it makes life much easier. Using metric system you don't have to convert inches to feets, feets to yards and yards to miles, and the conversion between length units means only moving decimal point. It is only a matter of efficiency.
I thought it sounded like one of those dumb questions you'd think are easy...then you come to find you can't figure it out. :D See, that still isn't what I'm looking for and since it is a dumb question I'm having a hard time finding something to put down. Is there anything you could think of that a scientist would use the metric system for? :)
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Metric was chosen as a standard system of units. It's also used by the entire world except the US and a small country I don't remember the name of. Everywhere else is metric.
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Still not what I'm looking for. :D
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Light years is an other example. Way more convenient for astronomers to talk in light years than 10^17meters
don't astronomers use parasec to measure inter-stellar distances? instead of using kg, it's more practical to express the mass of stars and planets in term of solar mass. even chemist/physicist use a.m.u to measure the mass of nuclei?
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Ease of use, complete range coverage, universality (additional units based on existing ones, like volume measured in units based on meter).
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don't astronomers use parasec to measure inter-stellar distances?
AFAIK both ly and pc are used.
instead of using kg, it's more practical to express the mass of stars and planets in term of solar mass. even chemist/physicist use a.m.u to measure the mass of nuclei?
In many situations it is much more convenient to use some specific scale, like mole. However, metric system is a common denominator that makes any conversion easier, faster, and less prone to errors. It doesn't make sense to measure anything in different units, it doesn't make sense to measure everything using the same units. Some balance is needed.
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Its also easier to measure pressure at sea level as 1 atmosphere rather than the "proper" SI equivalent of 1013250dynes/cm2.
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Is the dyne a metric unit? I thought is was Pascals...but maybe I'm cofusing SI with metric...?
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for your qn no.3 ... list all the examples in real life which show the efficiency of the metric system, easiest way to fill up an essay with pointless information :P
as for dynes... i though pressure was measured in pascals/newton squared metres?
dyne seems to me like the centimeter version of newtons.
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for your qn no.3 ... list all the examples in real life which show the efficiency of the metric system, easiest way to fill up an essay with pointless information :P
as for dynes... i though pressure was measured in pascals/newton squared metres?
dyne seems to me like the centimeter version of newtons.
That's what I was going to do but my mind is blank...what could a scientist be doing? How on Earth am I to guess what a scientist may be doing with the metric system? :D
Stupid question... :P
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everyday applications like figuring out much is needed for a cooking recipe, calculating your daily calorie intake, etc.
it doesnt have to be lab-based; heck, most people visualise scientists in white coats working with test-tubes in a lab. check out our member gallery photos and u'll know there's more to meets the eye than it is. ;D
if u really want to be specific, u can try what Borek said Ease of use, complete range coverage, universality (additional units based on existing ones, like volume measured in units based on meter).