Recent content by altegron

Thanks for the response, That makes sense -- I guess that means I should integrate from 0 to infinity then? \lim_{x\rightarrow\infty} \int_0^x cte^{-kt} dt = 1 Which is easier written as \int_0^{\infty} cte^{-kt} dt = 1 Which is: \frac{-(kt+1) \cdot e^{-kt} \cdot...

Homework Statement Consider a population of individuals with a disease. Suppose that t is the number of years since the onset of the disease. The death density function, f(t) = cte^{-kt}, approximates the fraction of the sick individuals who die in the time interval [t, t+Δt] as follows...

Okay, so this makes sense now. Really the key to the problem was the limit definition of derivative.

Well I know the slope of the tangent line at 3 is 9. But the limit at 3 is 30. I think what I don't understand is how to evaluate the limit. (Normally evaluating the limit is the same as plugging in a value into the function, but when it is like this and everything is divided by 0 I get...

Homework Statement Suppose y = 9(x - 3) + 30 is the tangent line to f(x) at x = 3. The limit I need to find: http://img259.imageshack.us/img259/2963/b3275332191bc2fc8561357mt3.gif 2. No Relevant equations The Attempt at a Solution Well I know that f(3) is equal to 30. So...

Because the question asks how many ions are present, you need to multiply the moles of sodium sulfate by the number of ions it breaks down into in water. In this case, I believe the Na2(SO)4 will dissociate to make two Na+ ions and one (SO)4 ion (total of 3 ions).

Basically my project is to present a method of removing Fe, Mn, Ca or Mg from water and then do an experiment on a sample of water with the heavy metal in it. I've been doing a lot of searching online so far, and most of what I have found does not relate. I need something that I can actually...

Edit: Just realized that maybe I should have posted this in a different forum... sorry about that. Basically my project is to present a method of removing Fe, Mn, Ca or Mg from water and then do an experiment on a sample of water with the heavy metal in it. I've been doing a lot of searching...

Thanks for the reply! Ah yeah that makes sense for (a). It should be plus or minus then. For (b), would the E from -q be -{k}_{e}\frac{q}_{x^2}?

Homework Statement http://img352.imageshack.us/img352/9444/enm1qi8.png Three point charges are arranged on the y-axis as shown in the picture. The charges are: +q at (0,a) -q at (0,0) +q at (0,-a) Any other charge or material is infinitely far away. (a) Determine the point(s) on the...

You should probably wait for someone more knowledgeable on this subject to post an answer, but here is what I came up with: It looks like you solved for s instead of the distance from q1 where the field is 0. If your problem looks like this: |----------s----------|...

Ohhhh I get it now! Thanks for the help!

Homework Statement http://img184.imageshack.us/img184/8125/chapter23number13qh8.png Homework Equations E = {k}_{e} \frac{q} {r^2} The Attempt at a Solution I figured that the electric field vector from the negative point charge would have to cancel out the electric field...