Recent content by TrueStar

Yes, we created a curve with our standard solutions. I looked around a bit more and it sounds very similar to a situation like this -- http://www.chemicalforums.com/index.php?topic=49489.0 I think we should be doing the same thing.

A lab mate and I are discussing how to properly interpret LCMS results and coming to different conclusions. We are taking a solid food sample and extracting it with 50:50 acetonitrile/water to determine the concentration of melamine in the food sample. Standard solutions were made that range...

I looked at the other similar threads earlier today and one of them seemed to be stuck in the same place I am. Like the poster, I think I was just missing part of the equation... V(r)-V(R)=∫E*dl Plug in everything and solve for V(r) which turns out to look like this. I tried to...

I still don't understand how to solve it. I figured out the electric field inside of an insulator however, and why it looks the way it does. E=Qr/4∏ε0R^3 Where r is the distance of a Gaussian sphere inside the insulator from the center to r. However, how would I know what r is, and...

Is it not the first relevant equation I wrote down? The change in potential is the negative integral of the electric field multiplied times the integral of the length...which would be the radius in this case.

Homework Statement Charge 6.00 is distributed uniformly over the volume of an insulating sphere that has radius = 5.00 . What is the potential difference between the center of the sphere and the surface of the sphere? Homework Equations ΔVab= -∫E*dl Electric field inside an insulating...

I figured out what I was doing wrong. It was a matter of entering the answer into the online homework program incorrectly, not so much that the answers were wrong.

Homework Statement Solve the matrix of differential equations with given initial values. dx/dt= (-6 2) x (-3 -1) Initial value is x(0) = -2 -5 Homework Equations (A-λI)=o The Attempt at a Solution My eigenvalues are -4 and 3 My...

I figured it out. The value within the log should be an absolute value as it came from the integral of the tangent.

Homework Statement Solve y''+25y=10sec(5t) Homework Equations NA The Attempt at a Solution I believe I have the correct answer for yp which is: 2/5log(cos(5t))cos(5t)+2tsin(5t) When I plug this into the Webwork field, it says it is incorrect. I checked my answer against...

Ah yes. I did it again from the beginning and was able to solve it correctly. Thanks for pointing out the error. :)

Homework Statement Solve the exact equation y^3-(14x+2)dx+3xy^2dy=0 Homework Equations NA The Attempt at a Solution I proved these were exact because dM/dy and DN/dx both equal 3y^2 I chose to work with N first and df/dy=3xy^2 Therefore f(x,y)=xy^3+h(x) I took df/dx of this and got y^3...

I've confirmed that this is correct. The online program wanted a t variable, not x.

Homework Statement Find the function satisfying the differential equation: dy/dx - 3y = 6e^(5x) with y(0) = -6 Homework Equations I believe this is Linear, so it is dy/dx + P(x)y = f(x) The Attempt at a Solution I chose -3y to be P and used it to obtain integrating factor e^(-3x). I...

I forgot the rule that Simon posted. It makes complete sense now. I will look at it the other way as well. Thank you both!