Recent content by praeclarum

OK. It's not as complicated as a double pendulum. It's just a single pendulum where the mass is constrained to a sphere (rather than the 2-dimensional case where you have a circle). Well, one thought I had was to solve for the potential energy of the system, since that's just mgh+1/2mv^2...

I thought of this question the other day, and I was unable to solve it. A Google search has not helped, so I thought I might post it here. A point mass hangs from a rod of length "l" from the center of a pendulum. The only forces acting upon the point mass are the force of gravity and the...

Here is why. As Borek mentioned, 8 is the number of electrons in the s and p orbitals. Why do atoms "want" to fill these? All atoms in a particular orbital, such as the 3s or 2p orbital, have the same energy, and the lower the number (the "3" in "3s," for example), the lower the energy of...

Let's say I have a mixture of silver and aluminum metal, and I just want the silver metal. How do I just get the silver metal and get rid of the aluminum? Also, if I have silver metal and I want to make silver nitrate, what molarity HNO3 should I add?

Well, why don't they form just the regular metal oxide? And why is superoxide superoxide more than peroxide with K?

Why do sodium and potassium form peroxides and superoxides when they burn?

OK...so from this, the short answer appears to be: (1) Ni+2 catalyzes reactions that create reactive oxygen species (peroxide, superoxide). (2) inhibits excision-repair of DNA. (3) cause gene silencing (more methylation of histones, less acetylation). Wow, I had no idea nickel did all this...

What is the mechanism by which these cations cause cancer?

Assume ~p. Then, by (1), q. Then, by (4), ~s. Then by (2), r. But ~(q^r). So it is a contradiction. Therefore, p.

Interesting! Thank you.

Nickel allergy is a very common allergy. It causes contact dermatitis. But why is it allergenic, being a metal. Recall that allergies are caused by an immune response. What exactly are you reacting to -- the nickel metal itself??

Why do we have to quantify over variables only -- why can't we quantify statements as well? Just out of curiosity... Does it lead to paradoxes or anything?

Ah, but I'm already familiar with a fair amount already -- I went through half of Quine's "Set Theory and Its Logic" (which is a bit more basic than Introduction to Axiomatic Set Theory). Perhaps I should finish that book (since it's a lot less terse in the explanations) ... I have plenty of...

Hi, I am a high school student, and I am trying to learn set theory (it's not for school - independent study; I love it). I have a book (Takeuti/Zaring Introduction to Axiomatic Set) Theory and I am going through it, but I feel like I'm going way to slowly (after trying to go through it for...

Even without assuming Choice, we can still apply what is known as "Epsilon Induction" to sets, assuming the Axiom of Regularity (ZF). Succinctly, it states that if A contains its powerset, then A must be the universe. http://en.wikipedia.org/wiki/Epsilon-induction There is also a...