RELATED RATES--help!

[psycheout]

Advertisement - Members don't see this ad

Folks, I have a calc final in TWO days. My book stinks. Would someone please give me a "formula" for setting up related rate problems, using calculus. Is there a method you use to organize your info every time, in the manner of say RICE tables for Gen Chem?
Maybe someone could post a problem and a solution?
I had a great ideal-gas-related rate problem on my last test that wasn't so bad.
Anyway, I'm gonna go try to pick apart the book and get some help. Thanks.

 

[Ross434]

Folks, I have a calc final in TWO days. My book stinks. Would someone please give me a "formula" for setting up related rate problems, using calculus. Is there a method you use to organize your info every time, in the manner of say RICE tables for Gen Chem?
Maybe someone could post a problem and a solution?
I had a great ideal-gas-related rate problem on my last test that wasn't so bad.
Anyway, I'm gonna go try to pick apart the book and get some help. Thanks.

You're given quantities, some information about their relation, and you're asked to solve for a change in one of these quantities over time. In order to do that, you'll need to set up an equation relating them, differentiate it, and solve. Often times you'll need to find a quantity that is not given (by solving it from your original equation) before you can sub in to the derived equation. Here's how to do it.

List all the quantities. Distance, volume, speed, angles, area, etc. Give a variable to each one. (distinguish which are rates and which are fixed quantities) Then find a relationship (equation) between the fixed quantities. Write down which ones are known. Often times, you won't know one of the initial quantities and you'll need to solve for it.

Next find the derivative with respect to time for the equation you made earlier. You'll plug everything into this one to solve for the one remaining quantity you'll need. (you're usually solving for the rate of something).

Make sure your equations only contain variables. This is what tricks a lot of people. Also, on a lot of problems, one of your rates of change in your final differentiated equation will be zero.