Recent content by whybother

But no one really expects the universe to be infinitely large anymore.

Yeah, because helping everyone have the means to take care of themselves is pretty much the end of society. /sarcasm

Look at this site: http://www.analyzemath.com/Tutorial-System-Equations/determinants.html for references to help And you can confirm your answers here: http://www.bluebit.gr/matrix-calculator/

Calculating the determinant for A, a 3x3 matrix with elements: a b c d e f g h i Det(A) = a(ei - fh) - b(di - fg) + c(dh-eg), by starting with row 1. So -15 is the answer you should be getting.

Use energy conservation + conservation of momentum. You know that since the sliding block isn't losing energy to friction, that all it's energy must be in the form of kinetic and potential energy. At the point it's released, all of it's energy is in the form of gravitational potential energy...

Just look at this picture and you should be able to see how to answer your questions, if you are at all familar with the normal distribution (which your question seems to be about). http://upload.wikimedia.org/wikipedia/commons/8/8c/Standard_deviation_diagram.svg

It's important to remember how the cross-product is defined before you look at this problem. The cross-product is an operation in a 3-D vector space that produces a third vector. In this case: (-1, 2, 0) \times (4, 2, 0) = (0, 0, -10) The cross product also gives you: a \times b =...

You can work on research for free, and if it's good, sense it to an academic (professor, pdf) that you respect and trust and they can help you get published.

Do you mean degrees, by certificates? Yes, in the academic community, having a PhD or a DPh is going to make you much more respected than someone with only a BSc. That being said, having reputable publications is also important if you want to be respected.

I'd consider using conservation of energy. At the point he grabs the rope, he has all kinetic energy and no potential energy. By the time the rope reaches its maximum height, it has no kinetic energy and all potential energy. It's at least a mental starting point for you to try, as long as...

Okay so you know the equations by which they grow for each of them, and then you set them equal to each other and solve for t.

That's not a unique formula. That's just combining the expression given for F with F=ma.

This thread is really hard to read. I'm surprised it hasn't been locked yet.

In general for 'doubling time' problems, we have a simple formula N = N_0 \times 2^{t \over T} where N is the number of bacteria after t minutes and T is the time in minutes that it takes to double. So if that's the relevant equation, attempting a solution should be possible. EDIT: Although...

I'm not sure how 'introductory' you are looking for, since you are (wisely) interested in mathematical rigor. I like Sakurai's Modern Quantum Mechanics for introductory stuff, his Advanced QM would be too much, I'd imagine. Cohen-Tannoudji's two parter is not bad for derivations either, I found.