Recent content by HuaYongLi

No, not for any exams in the future. But I don't like assumptions, I'm OK if the assumption if fundamental or it can't be explained with my current knowledge.

(2 dimensions.) Given 2 forces acting on an object (not modeled as particle), you can project their lines so that you can find a point of intersection - X. On this point of intersection exists no moment caused by the 2 forces since the line action makes 0 degrees with the forces. It follows that...

Sorry, my classmate used this account to post an question about his experiment I couldn't answer at that particular moment for him. I just realized that the answer is simply a rehash of Stoke's Law.

Could anyone please tell me how the acceleration of an object in a fluid varies with its velocity.

Thank You

Well I guess associativity, unique inverse and identity element are all trivial. What I'm having trouble with is closure, proving that for any elements a and b in the group, ab is also in the group.

Homework Statement G is a commutative group, prove that the elements of order 2 and the identity element e form a subgroup. Homework Equations The Attempt at a Solution I don't know where to even begin.

Thank You, I see it now. I failed to take into account that constructive interference isn't like destructive interference when dealing with this pairing up business.

Reading the derivation for the single slit diffraction minima formula from this site, I'm not convinced about its argument. http://www.math.ubc.ca/~cass/courses/m309-03a/m309-projects/krzak/index.html" What I'm having trouble understanding is the explanation of the formula for minima when m>1...

Thank you, I've gotten what I need to know.

I know the inequality can be used to find the minimum and how to manipulate it. My problem is how to actually come up with an inequality that will be of use in the first place, say I have (k-2)^{2}\geq0 - it's not going to be useful for our purposes when manipulated. Well, obviously one can see...

Anyone have some useful or nifty Firefox addons? I'll add mine here: (made using the infolister Firefox addon) * Adblock Plus 1.1.3 * ChatZilla 0.9.86 * Delicious Bookmarks 2.1.072 * DownloadHelper 4.6.5 * Fasterfox Lite 3.8.2Lite * Fission 1.0.9 - loading...

I encountered a question in my book: a)An electron is trapped in a solid between a group of atoms where the potential is +2.8V The de Broglie wavelength of this electron is 1.2nm. Calculate i) its speed ii) its kinetic energy iii) the sum of its kinetic energy and its potential energy b)i)...

Yes, but is this a matter of just thinking of a quadratic inequality that when manipulated will give desired terms k and 1/k?

Maths