/sci/ - Science & Math

reciprocals.

>>1949443

wut

>>1949452
It's a hint to solving the problem. If you still can't figure it out, you shouldn't be using a computer, you're not smart enough.

guise, halp pl0x

Ask your teacher. If you can't figure out this kind of simple problem, you're in the wrong math class and need to move back down a level.

i pay tax dollars for your fucking teacher to be teaching you this crap, it's not my job to teach you myself. i want my fucking money back

fuck you guys

i pay tax dollars for your fucking teacher to be teaching you this crap, it's not my job to teach you myself. i want my fucking money back

sorry forgot my greentext
>i pay tax dollars for your fucking teacher to be teaching you this crap, it's not my job to teach you myself. i want my fucking money back

just tell me the answer so i can figure this out myself

>>1949513
>>i pay tax dollars for your fucking teacher to be teaching you this crap, it's not my job to teach you myself. i want my fucking money back

if you're from the US you didn't pay for my education

>>1949528
wow then your country is shit tier. where you from, so I know where to put you on the tier list?

>>1949537

venezuela

>>1949439
3.333.... minutes.

>>1949541
Geez, you're giving us a bad name. Why can't you figure it out with hints? What exactly is the problem that you're encountering?

>>1949549
oh, you are going to want an explanation arn't u?
... very well.
lets say each tank has 60 units of water (its arbitrary, it doesn't matter, the point is that they have the same capacity.) for tank A to empty in 4 minutes it loses 15 units of water per minute(60/4). tank B empies in 5 minutes, so it loses 12 units of water per minute. (60/5)
for tank A: 60-(3.33X15) = 60 - 50 = 10 units left at 3.33 minutes
for tank B: 60 - (3.33X12) = 60 - 40 = 20 units left at 3.33 minutes
20 is twice as much as 10, so at 3.33 minutes, tank B is twice as full as tank A.

>>1949568

lol i dunno

here's what i did:
volume of the first tank V1 = 4-t
volume of the second tank V2 = 5-t

so to find out the value of V1 when V2 is half I did V1=V2/2
solving for that resulted in t=3

its kinda close to what >>1949574 found, maybe its in the right path but some detail is wrong?

It's unreasonable to assume that a tank drains at a constant rate. Better to say it drains at a rate proportional to the pressure at the outlet, which is in turn proportional to the amount of water remaining in the tank. Still, this is not entirely accurate.

As this model results in a tank that never drains completely, you'd have to choose some small fraction of the original volume at which the tank is considered "drained". Maybe 1%.

For each tank, you'll wind up with an expression that looks like:
V(t) = V(0) e^(-ct)
Where c is a constant relating drain rate to instantaneous volume. C will be different for both tanks. You can then use those two equations to determine when V1(t) = V2(t) / 2

>>1949657

well if I don't consider the flow as a function of pressure, my solution in >>1949608 is right?

>>1949608
If you look at t = 0, your two water tanks don't have the same volume. You'd just have to adjust the equations to (4-t)/4 and (5-t)/5

>>1949657

depends completely on tank. for small opening, it is so close to constant it wont matter...
i wouldnt say it is unreasonable, but i agree it is not an universal usable simplification.

>>1949703

awesome, thanks!

>>1949549
>>1949574

assuming a constant rate, then she is correct. otherwise, not.
and i don't know how to work it out if the rate of flow changes proportionally to the amount of water left.

>>1949574

lololol tank drains at a constant rate

wait till you have negative volumn

>>1949775
nah, i'm presuming the tanks stop draining when they become empty.
3.33 recurring minutes is correct...or 3 minutes 20 seconds, i should say :)