Stupid Definition and 300 Threads

as uploaded. I think the example is very weird. Why we can use conservation of momentum? There is external force! thx.

Stupid Question about Python Learning Curve :D Sooooo... I have to get some sort of menial minimum wage job in the near future, and I would be okay with this if it gave me the time to study books or think about philosophy (a night clerk/cashier or something, etc.) Regardless of what...

Suppose we want to express the vector v = (1,-2,5) as a linear combination of the vectors u = (1,1,1) v = (1,2,3) w = (2,-1,1) We follow the method here: x \ \begin{bmatrix} 1 \\ 1 \\ 1 \end{bmatrix} \ + \ y \ \begin{bmatrix} 1 \\ 2 \\ 3 \end{bmatrix} \ + \ z...

Why \lim t_n >-\infty\Rightarrow inf\{t_n:n\in\mathbb N\} >-\infty?

Homework Statement There are two rigid plates on the ends. In between them are two steel plates and one aluminum plate. The aluminum one is in the center. When the temperature increases enough the aluminum will buckle and touch one of the steel plates to close the circuit. alpha(alum)...

1. Is closed ball the derived set of open ball? 2. In discrete metric space, boundary of a set is always the empty set?

is the equation f(x)=(x^2-1)/(x+1) continuous? i know it can be reduced to f(x)=(x-1) but i remember that in doing so you divide by zero for x=-1 and thus it will be discontinuous at that point... i don't know I'm really tired tonight

Does dx/dv = t ? Can you just manipulate equations like this? [ x is position and v is velocity, t time :P ] Stu

Wigner's representation theorem says that any invertible transformation between rays of a Hilbert space that preserves transition probabilities can be implemented by a transformation on the Hilbert space itself, which is either unitary or antiunitary, depending on the particular transformation...

I hope this is the right place to post this... I've been having trouble with Skype lately. I can't play online games (I've been struggling with League Of Legends lately) while I'm on skype. The problem is skype, and I assume this shouldn't be happening since I know people with less bandwith...

Does this "product" satisfy a need? http://www.snazzynapper.com/

Homework Statement I got a Problem that says: In this Problem we consider the angular momentum, \hat{L}, which normed common eigenstates for \hat{L}^{2} and \hat{L}_{z} is described by \left|l,m\right\rangle, where l and m is the corresponding quantum numbers: \hat{L}^{2}\left|l,m\right\rangle...

so i came up with a proof that..well.. Let L/K be a field extension and we have defined the norm and trace of an element in L, call it a, to be the determinant (resp. trace) of the linear transformation L -> L given by x->ax. Now it's well known that the determinant and trace are the...

I don't know why I can't think of an answer to this, but it should be simple. Every human cell contains 46 chromosomes, right? Well why do they only show 2 chromosomes in the diagrams you see that depict mitosis?

Hello, I am new to this forum and signed up to ask this specific question. From what i understand of evolution(which i am not trying to discredited here btw :cool: ) mutations are caused by either chance or adaption which then through natural selection favorable mutations are basically breed...

0.10 mL of oil can spread over a surface of 40 m^2 of water in a film one molecule thick to prevent the water from evaporating as fast. If one nanometer is 1 x 10^-9 meters, what is the length of one oil molecule in nanometers? Ok so this is a really stupid question, but I got the correct...

Homework Statement racing driver, David Purley, survived a deceleration from 173km/h to 0km/h in a distance of 66cm in a crash. body mass = 55kg Homework Equations V^2=u^2+2*a*d is what i have to work with at the moment, i was thinking of using a=Fnet/mass. but I am having trouble...

Homework Statement Okay I've basically solved this problem... but I need some clarification. The problem is "The acceleration of an object is given as a function of its position in feet by a=2*s^2 ft/s^2. When s=0, it's veloctiy is 1 ft/s. What is the velocity of the object when s=2 ft...

Do you know anyone that wanted to get into a Grad School into the United States so bad that they became U.S. Citizen and then apply?? And they actually got accepted??

how the conduction band offset varies with Al concentration?? what is the different?

How does the standard model reflect inertial energy ? The following puzzles me- I am reliably informed that the entire milky way is moving through space towards a nearby galaxy cluster at a heady speed of 1000 Klm per second. I assume this scenario is repeated all across the Universe with...

Why do we see a continuous spectrum of radiation for blackbodies when we know that energy in atoms are quantized thus only emitting discrete energy levels?

Homework Statement Hi, I have two stupid questions about Peskin's QFT book. (1) P23, How to derive from (2.35) to (2.36) (2) P30, How to derive (2.54) Homework Equations (1) (2) The Attempt at a Solution (1) If I consider the dual-space vector, \langle \mathbf{q} | = \sqrt{2...

Homework Statement A pendulum consisting of a small heavy ball of mass m at the end of a string of length l is released from a horizontal position. When the ball is at point P, the string forms an angle 30 degrees with the horizontal. a. Free body diagram (all set on that) b. Determine the...

Homework Statement Find the voltage V and the power absorbed by the 12-ohm resistor. http://i.imgur.com/xCTEI.png Homework Equations p = vi v = ir KVL KCL The Attempt at a Solution Tried using KVL and KCL in various ways. This book gives horrid examples.

Suppose I have a perfectly constant, uniform magnetic field extending over space. Now I imagine a circle in this space. Now I imagine the circle is growing larger. The magnetic flux through this imaginary circle is, therefore, increasing. Therefore, there must be an induced electric field. But...

I'm don't think these people were joking when they wrote this article: The article is filled with claims like this from all over: If it is a make people stupid weapon, it seems to be working quite well.

Homework Statement A car travels up the hill at a constant speed of 30 km/h, then returns down hill at the speed 66 km/h. Calculate the average speed round trip I can't believe I am stumped on such a kindergarten problem, I hate online homework and the garbage system they are designed on...

When I read quantum field theory in Weinberg's Volume 1. In equation 2.6.22 : P{\Psi _{p,\sigma }} = {\eta _\sigma }\exp ( \mp i\pi \sigma ){\Psi _{{\cal P}p,{-\sigma} }} I don't agree with the -\sigma in the result of space reversal transformation. Can anyone explain it for me? Thanks

Homework Statement This is a 2nd order perturbation theory question, but I've got it boiled down to the following sum, which I need to determine where (and if) it converges: E_n^{(2)}=\sum_{n\not=...

Slow, stupid computer/printer face! So I has a question to AXE. I swear, whenever I try to print a .pdf file that opens in firefox, it takes FOREVER. The printers are on a wireless network but I swear to all that is holy and good that it takes like 5-10 minutes to print. Oh and that's not time...

So is it true that if you have a constant velocity therefore you have no change in acceleration so A=0 and if you have no acceleration then you have no Fnet? And is that the case in ANY force problem? Thanks!

OK, first of all, I wasn't really sure where to post this; it's not really homework because we covered the material weeks ago and moved on, leaving me totally in the dark. My physics teacher has this annoying habit of saying something is "ALWAYS true" or "NEVER true" and then beginning the next...

I want to create documents using LaTeX. I have: MiKTeX TeXnicCenter Ghostscript GSview Mathtype v. 5.0 I want to create documents, but I have no idea how to start, this all seems foreign to me. Assume I am a stupid High School Sophmore who doesn't know anything.

Hi, I have a question that has stumped me for a while, well its been a while since I have done any academic work and its annoying me that I just can't work it out. Here it is:- You have 3 propellers, we shall call them A, B and C Propeller A is a small propeller Propeller B is a...

Follow my lead, let's make a list of things you thought as a kid or kids think about when they imagine being older that are sooooo not true. You'll get the hang of it. 100. Adults don't have bed times. 99. Being independent and on your own is awesome 98. Driving is fun 97. Turning 18 means...

Hi, I havn't been on these forums for years now probably, I googled something and this site came up. I see some people on here I remember. The title really states my problem, I was wondering if anyone else feels this way? It's strange, I used to be very focused on work, competitive...

So my mother mentioned to a co-worker, who is a "math guy," that I was interested in math. The co-worker subsequently gave her a piece of paper with the following written on it to give me to to "solve" or "prove" in my mother's words, yet I am unsure what to do. Here is what was on the paper...

:smile: Okay then! Let's say we are ONLY working in the 1st Quadrant of the x-y plane. I have some vector in that region that makes some angle with the +x axis. I then rotate that vector through some angle. The initial points of the vector before and after are coincident, i.e. I only...

I've been trying to get my head around relativity etc and struggling :-( However there's one thing that I can't find much information about at an interested-layman level - gravitational waves. They're described as having a frequency etc (being waves) and traveling at light speed. But if they...

Hi all. In the building I live in, some people I know have removed the ground plug from their three-pronged appliances in order to plug them into the house's older, two-wire setup. There is only a limited number of 3-conductor outlets in the house. I've urged them to stop doing this because...

Homework Statement Would 85 uV (Micro) be 8.5 x 10^-5 V ? And would 600ps be 6x 10^-10 S ? Ehhh I haven't slept in weeks, I just can't focus. Homework Statement Homework Equations The Attempt at a Solution I used the fact that 1u = 1x 10 ^-6 and then I used 1V/1000000uV x (85 uV) and for...

Hi all, I am experiencing some problems in solving this simple problem regarding optimization. Here it is: A fitness center charges $500 for each registration per group of 20 people. The cost will diminish by $5 every time a new member registers. For example, if the group is now formed...

I know that there is a theorem to calculate the coefficients for a multinomial expansion, but I'm having a hard time implementig the algorithm. What I need to know is if my procedure is correct: (A + B + C + D)^n = \sum_{i=0}^n \dbinom{n}{i} A^{n-i} (B + C + D)^i = \sum_{i=0}^n...

Stupid hollywood and previews! Ugh, I just got back from seeing Wolverine and i swear, I'm so sick of previews showing every good scene in the movie. It also seems like a full 1/2 of the good scenes in previews occur in the first few minutes of every movie! It's like the beginning of movies are...

So I am trying to follow along this example in the text to find keq of the system. I can follow everything up until the point that they say: "It follows that x=2(x1+x2) where: x = displacement of mass x1 =displacement of Pulley1cm x2 =displacement of Pulley2cm I am not...

So the current (and classical) opinion on education is that a well-rounded education is best for students. The definitions of well-rounded are a bit muddly and mean different things to different people, so I was curious; what subjects should a 'well-educated' person know or at least be competent...

Richard Dawkins says Pope is 'stupid' Whether correct or not, this seems like a very outspoken statement, even for Dawkins.

THe answer given is C: All of these Now, are A & C not equivalent?

Okay, so the object of this program is to write my name using an m x n array so that it prints each letter made up of that letter. That is, the first letter is B and thus is made up of a bunch of B's. Here is my code...I do not know what the problem is? #include <iostream> #include...