physics lols (was 'maths lols')

[m00`]

how do you convert

11.6cm^-3
to
m^3

any mathematicians here

[Snack]

Per Kubic Centimeter -> Per Kubic Meter = 11 600 000 m-3
Per Kubic Meter -> Liter = 1160L
Liter -> Kubic Meter = 1,6m3

At least that's what i make of it

[m00`]

i guess that makes sense are you 500 million % sure?

[Snack]

Not with an E for maths <_<, but I have a very helpfull book for that.
I'm sure.

[VijchtiDoodah]

1 cm³ = 10^-6 m³
or, for clarity:
1 cm = .01 m
and
1 cm³ = .01³ m³ = 10^-6 m³
therefore:
11.6 / cm³ = 11.6 / 10^-6 m³ = 11.6/10^-6 m^-3
= 11.6 x 10⁶ / m³

I've added a few unnecessary steps just to be certain you understand what's going on. It's also in simplified scientific notation, if you're unfamiliar with this I can write it in a different way (though you should be able to figure it out). And don't forget to add units for the numerator: it's bad form to leave it the way it is.

What is this for, by the way?

[Snack]

I hate my calculator now.

Already did.

[m00`]

1 cm³ = 10^-6 m³
or, for clarity:
1 cm = .01 m
and
1 cm³ = .01³ m³ = 10^-6 m³
therefore:
11.6 / cm³ = 11.6 / 10^-6 m³ = 11.6/10^-6 m^-3
= 11.6 x 10⁶ / m³

I've added a few unnecessary steps just to be certain you understand what's going on. It's also in simplified scientific notation, if you're unfamiliar with this I can write it in a different way (though you should be able to figure it out). And don't forget to add units for the numerator: it's bad form to leave it the way it is.

What is this for, by the way?

thanks man. oh its for a physics question but I have to convert a unit so I can shuve it into the equation. I have a lot of problems with converting units

btw thanks to you too snack you sexy hunk of flesh

[PQ]

what's 11.6cm^-3?

something at -3 dimensions? Or is it some random unit 11.6 every cm^3?

[VijchtiDoodah]

The exponent is negative, so 11.6 cm^-3 is the same as 11.6 / cm³. This is a ratio, so it's saying that for every cubic centimeter the result increases by 11.6.

To clarify, think of 11.6 as dollars. If you wanted one 1 cm x 1 cm x 1 cm brick (1 cm³), it might cost you 11.6 dollars. Therefore you could write the cost of any volume of brick as:
Total cost of V volume of bricks = ($11.6 / cm³) x V cm³. That's 11.6 dollars for every 1 cm³ of bricks.

Do you understand now?

[Kazuki]

This doesn't make sense. Vijcht worked through it properly, but the reason that it doesn't make sense to me is because it would mean that you are given 11.6 of an unknown unit per cube centimeter and are asked to find out how much of that same unknown unit you would have per cube meter. It's an unusual problem for a physics conversion, if you ask me. It almost seems to me like m00 meant to type "convert 11.6 * 10^-3 cm to ___ * 10³ m".

You sure you typed it right, m00?

[m00`]

yeah I definitely typed it right

[VijchtiDoodah]

I was assuming m00 just left out the units, Kaz. Why don't you post the entire problem so that we can help you better, m00.

[m00`]

Near Earth, the density of protons in the solar wind is 11.6^cm-3, and their speed is 704 km/s. (a) Find the current density of these protons. (b) If Earth's magnetic field did not deflect the protons, what total current in amperes Earth receive?

for a)
I am using J = nqv
n = 11.6^cm-3 = xxxxx m^3
q = (1.6x10^-19)C
v = 704 km/s = 704000m/s

when i put n = 11.6x10^6
I get J = 1.3 x 10^-6 A/m^2
am i right?

and yeah i don't get b)

i should get this topic renamed to 'physics lols' aye

[Serial K!ller]

You can use google to convert units:

 Type : 11.6 cubic cm = ? cubic m
 answer = 1.16 × 10^(-5) cubic meters

You can also use google also to calculate with units so you don't have to convert them or use it as a check at the end:

 Type : 11.6/cubic cm * 704 (km/s) * 1.6*10^(-19) coulomb
 answer =  1.306624 × 10^(-6) A / m2

[PQ]

The exponent is negative, so 11.6 cm^-3 is the same as 11.6 / cm³. This is a ratio, so it's saying that for every cubic centimeter the result increases by 11.6.

To clarify, think of 11.6 as dollars. If you wanted one 1 cm x 1 cm x 1 cm brick (1 cm³), it might cost you 11.6 dollars. Therefore you could write the cost of any volume of brick as:
Total cost of V volume of bricks = ($11.6 / cm³) x V cm³. That's 11.6 dollars for every 1 cm³ of bricks.

Do you understand now?

I did understand your answer, but answering your question with a random/unknown unit just made me think that he mistyped the 3 as a -3. (but it was fine it seems)

A is right,


b ->

the electric charge of a proton is 1.602*10^-19 C (1.60*10^-19 A/sec), if you just multiply that by the surface of the earth in cubic cm, multiplied by 11.6, you'll get the amount of coulombs. Division that by the amount of time and you'll get the amperes. (right?)

edit: drunk typo's

[m00`]

I don't get b still

[chutem]

You can use google to convert units:

 Type : 11.6 cubic cm = ? cubic m
 answer = 1.16 × 10^(-5) cubic meters

You can also use google also to calculate with units so you don't have to convert them or use it as a check at the end:

 Type : 11.6/cubic cm * 704 (km/s) * 1.6*10^(-19) coulomb
 answer =  1.306624 × 10^(-6) A / m2

Only problem is you can't use google in exams.