View Full Version : Calculus Homework
(1 pt) A voltage V across a resistance R generates a current I=VR . If a constant voltage of 5 volts is put across a resistance that is increasing at a rate of 0.5 ohms per second when the resistance is 5 ohms, at what rate is the current changing?
Any help? Due in 33 minutes. I know, short notice, but if you can help, please.
ok i got an answer of -.1 ohms/sec. It's saying my units are wrong though. The example in my textbook has ohms/sec though. Is there another name for ohms/sec?
Don Corleone
11-30-2006, 04:56
It's asking for the rate of change of current, not the resistance. Current is in amperes or milliamperes, so the units would be A/sec or mA/sec.
Don... 2 minutes after it was due. :wall: :wall: :wall: :wall:
Thanks for the help though, it was Amp/s.
Sasaki Kojiro
11-30-2006, 05:33
I believe the correct answer is: Gah!
CrossLOPER
11-30-2006, 06:40
The Org does not like doing your homework for you.
Uh.... .25 amperes per second. I would have answered before the due date, but, you know...video games. Anyway, this is university homework?
The Org does not like doing your homework for you.
Unless you are willing to pay that is ~:pimp:
stop being a wuss and asking people on this board to do your homework for you!
just man up and say your dog ate it like we all did it! :laugh4:
Don Corleone
11-30-2006, 16:00
Uh.... .25 amperes per second. I would have answered before the due date, but, you know...video games. Anyway, this is university homework?
See, now helping him with the units is help. Giving him the answer... well.... more than I was willing to do.
Just so you understand Ice, the one constant in the equation is the voltage.
V=IR. If you take the derivative of both sides, dv/dt = R dI/dt + I dr/dt (using the chain rule). Now, you since voltage is constant, dv/dt = 0. Solving the rest is just algebra and plugging in the answers they gave you. If the initial resistance was 5 ohms, the initial current was 1A. Solving the above equation does indeed yield that dI/dt = -I/R dR/dt = -(1/5)*0.5 = -0.1 Amps/sec or 100mA/sec.
Are you an EE Ice, or is that just an example equation from your calculus book to 'keep it relevant'?
E to the X, dy dx,
E to the X, dx,
Tangent Secant Cosine Sine,
Three point one four one five nine,
Square roots Cube roots Poisson brackets,
Dis-integrate ‘em Yellow Jackets!
:cheerleader: :cheerleader: :cheerleader: :cheerleader:
@Everyone complaining about me asking for help:
I would say (insert word) off, but I'm not allowed for obvious reasons. I had asked about 10 people from my class for help on that ONE problem, and no one knew how to do it. I don't see the harm in asking. It's not like I posted my entire assignment.
@Gore:
Yeah it's university homework. I'm retaking Calc I, even though I could have gone to calc II. I just needed a Calculus course for my major and I didn't want to take Calc II.
@Don:
I'm not an EE, but a business major actually. Like I said to Gore, I just need this math class for my major requirement.
Myrddraal
11-30-2006, 20:05
An EE would be doing vector calculus :p
Sasaki Kojiro
11-30-2006, 20:07
:cheerleader: :cheerleader: :cheerleader: :cheerleader:
You stole our fight song :furious3:
(except for the last two lines)
You stole our fight song :furious3:
(except for the last two lines)
What are your two last lines?
Sasaki Kojiro
11-30-2006, 23:41
What are your two last lines?
e to the i, radical, pi
fight em fight em wpi
Anyway, this is university homework?
Yeah it's university homework. I'm retaking Calc I, even though I could have gone to calc II. I just needed a Calculus course for my major and I didn't want to take Calc II.
We get harder stuff at my high school. Should have gone to America :wall:.
We get harder stuff at my high school. Should have gone to America :wall:.
So did I. Just didn't know what an amp was.
doc_bean
12-01-2006, 10:55
So did I. Just didn't know what an amp was.
That was third year HS over here (which would have made it first year in the US system, we don't have junior high).
No wonder your universities ask that much money to teach you guys, it sounds like a lot of work :laugh4:
Duke Malcolm
12-01-2006, 13:20
Learning Calculus? In university? Good lord. We did that when I was 14/15...
Now in Advanced Higher we are imagining numbers, and doing advanced Integral and Differential Calculus...
In Physics, we do wave and electricity phenomena... and angular motion...
In Chemistry, we do more on Organic Chemistry, Principles of Reaction (Stoichiometry, Equilibria reactions (acid/base buffers, indicators, et al), Electrochemistry) and Quantum Mechanics and Electron Structure.
Big King Sanctaphrax
12-01-2006, 14:13
So did I. Just didn't know what an amp was.
What?! You didn't learn what an amp was in high school?! I think they initially introduced basic electricity concepts in year 8 over here, in which I would have been twelve.
That's really shocking.
That's really shocking.
Nice pun. :2thumbsup:
Big King Sanctaphrax
12-01-2006, 17:08
When you're as innately funny as me, it's hard to avoid them.
Sasaki Kojiro
12-01-2006, 17:50
lol. We do have calculus and chemistry and physics in high school here in America. I don't remember any of it because it's not my field which is why I suspect Ice doesn't know it.
They offer skippable classes freshman year in college for people who didn't learn them very well in high school.
Learning Calculus? In university? Good lord. We did that when I was 14/15...
Now in Advanced Higher we are imagining numbers, and doing advanced Integral and Differential Calculus...
In Physics, we do wave and electricity phenomena... and angular motion...
In Chemistry, we do more on Organic Chemistry, Principles of Reaction (Stoichiometry, Equilibria reactions (acid/base buffers, indicators, et al), Electrochemistry) and Quantum Mechanics and Electron Structure.
God Bless the Scottish education system, and all it's lovable SQA-defined-parameter nonsense...I just wish they didn't place such a big emphasis on carbon compounds...they smell (literally too heh, get the ester reference? Good times).
On a less nostalgic note, this could make for an interesting discussion: which country has the most challenging education system? I have always been led to believe America's was pretty simple. I once watched a High School reality program where the seniors were learning about Moles, Gram Formula Mass and other chemistry fundamentals (which are taught here at age 14, standard Grade level.)
Also no offense meant, I am not implying Americans are stupid :beam:
Sasaki Kojiro
12-01-2006, 18:19
Could be. I took biology 9th grade, chemistry 10th&11th and physics 12th. Obviously in their high school they do it in a different order?
doc_bean
12-01-2006, 19:16
Belgium has a pretty 'hard' education system if you take the harder 'packages', however, since it's thought in packages it doesn't allow for much flexiblity to make it even harder.
I remember we had integrals in the last year but we didn't see organic chem like some other people seem to have had (in their system).
Big King Sanctaphrax
12-01-2006, 19:18
Could be. I took biology 9th grade, chemistry 10th&11th and physics 12th. Obviously in their high school they do it in a different order?
So you don't have to take all the sciences in all of the years?
I did a massive amount of organic chem in school, it was extremely annoying.
Sasaki Kojiro
12-01-2006, 20:09
So you don't have to take all the sciences in all of the years?
I did a massive amount of organic chem in school, it was extremely annoying.
Yeah one a year. In the year I took physics we did mechanics, electricity, and magnetism.
In calculus integration was chapter 5 out of the 13 we did.
Duke Malcolm
12-01-2006, 21:13
God Bless the Scottish education system, and all it's lovable SQA-defined-parameter nonsense...I just wish they didn't place such a big emphasis on carbon compounds...they smell (literally too heh, get the ester reference? Good times).
All that organic chemistry only comes in useful when 7 out of 23 suggested Advanced Higher Investigations involve making ethanol by anaerobic respiration in one way or t'other...
Vladimir
12-01-2006, 21:25
Oh yea? Back when I was in High School we lad to learn quantum mechanics using an abacus (sheesh people, what ever happened to walking 5 miles in the snow?).
Edit: Curse the gods, first post on page 2 :furious3:
Duke Malcolm
12-01-2006, 22:40
Oh yea? Back when I was in High School we lad to learn quantum mechanics using an abacus
Abacus? We don't even have the luxury of an abacus! What I would give to have an abacus!
(sheesh people, what ever happened to walking 5 miles in the snow?).
5 miles? Egad, we walked 15 miles for 4 days out in the cold, wind, rain and snow! Wearing the same clothes and carrying all our belongings on our backs. Psh...
It all depends on your field. It seems like it differs in America because they actually let you chose what you want to take, wheather it be hard, easy, science, english, mathmatics, or etc.
Saski is correct. I know some kids that took many years of Physics, Calculus, and other math classes in high school. I focused more on business classes and chemistry/biology because I thought I might have wanted to be a doctor. They don't shove things down your throat that you don't want to take.
For the last time, I've taken calculus before. I scored very well on the Advanced Placement test, and could have skipped to a higher course, but it's not necessary for my major, so why torture myself?
vBulletin® v3.7.1, Copyright ©2000-2025, Jelsoft Enterprises Ltd.