Beginning Definition and 179 Threads

I found this on wikipedia: Indeed, such a treatment of infinity is ridiculous, but treatments exist in our head and not in the universe. The universe did exist for an infinite time, but us humans have chosen to begin counting from a certain point, which is why an infinite past is possible...

Homework Statement (a) A luggage carousel at an airport has the form of a section of a large cone, steadily rotating about its vertical axis. Its metallic surface slopes downward toward the outside, making an angle of 18.0° with the horizontal. A piece of luggage having mass 30.0 kg is placed...

The announcement and discussion thread is here. Please also read page 2 of the applicable rules. https://www.physicsforums.com/showthread.php?t=459349

Homework Statement greetings why a bulb glow dimmer in beginning and then brighter when it is connected to a inductor?

Let G denote the set G = {f : R → R | f is infinitely differentiable at every point x ∈ R}. Prove that G is a group under addition. Is G a group under multiplication? Why or why not? I have proved this after much trouble, using the axioms of group theory, and I think I understand the...

Homework Statement Ann T Matter (yeah, my teacher is that lame) (weight 600 Newtons) is falling through the air at a terminal velocity of 120 mph. How much friction is acting on her? Homework Equations none were given to us to use. but I'm not sure if that means that we shouldn't use any...

If energy cannot be created or destroyed, that means all the energy that ever was and ever will be already exists. Wouldn't this mean that the universe has always existed? ..in one form or another. Everything that dies here on Earth goes back to the planet and new life is created. The universe...

The Big Bang, Entropy Destruction, and the Beginning of the Universe? So for a while now I've been pondering the ideas of times arrow, the creation of entropy and disorder, and ultimately how the higher order state of the universe all originates with the big bang. According to modern cosmology...

I've been working through the book The Story of i(sqrt of -1). It's kinda like a story with a lot of Math. The first 2 chapters deal with cubics and geometry for solving cubics functions. I understand the algebra behind it but I'm getting lost with the big picture. I need a supplemental book or...

Homework Statement Homework Equations conservation of energy The Attempt at a Solution how can the energy at the beginning be zero. then get accelerated? umm proton goes to lower potential and electron goes to higher potential? correct? i think that electron gets pulled by the higher...

What advice will you give to someone who starts as a graduate student (theoretical works) but since supervisor is rarely available for consultation, have to take the responsibility of making progress alone. Frankly I am in such a situation and even though I work a lot, I find I am making very...

I am new to this and am trying to implement Split Spectrum Processing (Delta-K processing) to ENVISAT ASAR coregistered images. Am using IDL for this, which is quite similar to MATLAB. Does anyone have some information on how to go about this as I am not able to understand the relation between...

Homework Statement Let A_1, A_2... be any infinite sequence of events, and let B_1, B_2... be another infinite sequence defined as B_1=A_1, B_2=A_1cA_2, B_3=A_1cA_2cA_3 and so on. Prove that Pr(Union i=1 to n A_i) = Sum i=1 to n Pr(B_i). (sorry if that notation is hard to understand)...

I've posted this in the Geometry & Topology section, but I believe it will get many more views here, so I'm posting a link Pictures here: https://www.physicsforums.com/showthread.php?t=407776 --- I really liked Penrose's diagrammatic way of writing tensor algebra, so I spent a while...

I really liked Penrose's diagrammatic way of writing Tensor algebra, so I spent a while learning the basic notation. Unfortunately, it took a very long time for me to learn this because there is so little info on it to begin with. I also didn't see much mention of how to use the notation for...

Hi I'm beginning to take physics a little more serious than ever and starting with maths. just want to know if there is any advice on what materials to get for my long studies? Thanks

Homework Statement I originally made this thread for something else, but I have another problem that I need help with. Suppose a and b are nonzero real numbers. Prove that if a < 1/a < b < 1/b then a < -1. Homework Equations A hint was given for the problem: Assume a < 1/a < b <...

For a while now I have been looking for a series of texts that I can read in order to learn some of the basics of abstract/pure mathematics. I am currently taking Calculus II with Stewart's book as my text, and this summer I plan on going through Spivak's Calculus. I have finished my...

Homework Statement intergral from pi to 0. of (sin(3t)dt)^4 The Attempt at a Solution okay so i know how to do this but when i tried substitution putting 3t=u and (1/3)du= dt i always came with the the wrong coefficient at the end with the answer and so i would multiply it...

Hello. I'm currently doing my masters in Information Science, and I did my graduation in Life Sciences. While I did have a course on Calculus at the 11th and 12th grades, I've forgotten most of it now. I wish to start out with Calculus and Analysis again. My approach to Calculus and Analysis...

Q: A uniform line charge that has a linear charge density λ = 4.4 nC/m is on the x-axis between x = 0 to x = 5.0 m. (a) What is its total charge? (b) Find the electric field on the x-axis at x = 6 m. (c) Find the electric field on the x-axis at x = 11.0 m. (d) Find the electric field...

The big bang states that time/space was a product of the expansion of the initial singularity of our universe. Now in order for our universe to initiate the big bang, causality must be invoked to start inflation, hence started time itself. But, how can causality be invoked if there is no time to...

i'd like to know if the shot at the beginning of Wanted when the man shoots the other man from inside his house and kills the assisin on the roof is possible.. it seems that it was in the air way too long, was resisting gravity, and could no longer be considered a projectile because it looks as...

I know this question has been asked before, so please don't assume I didn't browse the archives. I just want some additional opinions. I have limited experience with quantum mechanics, so assuming that I'm starting from absolute scratch, what would be a good way to teach myself quantum...

Children are incapable of fending for themselves. It seems most insects and animals are hard-wired for survival at their birth/creation. Human babies are completely defenseless. This would seem to point to the fact that the first humans could not have been children or would have needed a...

[b]1. These are calculations for a roller coaster project where we had to find the height, GPE, velocity, KE, and total ME. Question 1: what percentage of the total beginning GPE was converted to final kinetic energy? Question 2: What percentage of the total beginning GPE was converted to...

Homework Statement Antartica is roughly semicircular, with a radius of 2000km. The average thickness of its ice cover is 300m. How many cubic centimeters of ice does Antartica contain? Assume we ignore the curvature of Earth. Homework Equations (4/3 Pi r^3h)/2 The Attempt at a...

any suggestions?

Being no more than a pop-sci reader in this subject, I'd like to ask the experts a naive question: At that instant where the entire universe was concentrated at a single point, it seems to me all matter had a definite position and momentum. Isn't this a spectacular fall of the uncertainty...

I am creating a calculator and have 4 textboxes. I need to know what functions I need to delete the number '0' from a string of numbers such as, "0852" so it can look like "852." My goal is for the program to check the user input after the user has pressed the 'enter' button to go to the next...

"Undergraduate" or "beginning" mathematical methods book? Hi everyone, I'd like to know your recommendations for an "introductory" mathematical methods book. I have a book by Frederick Byron and Robert Fuller...that's a good book, but it seems suited for the grad level. I'm looking for the...

1. Homework Statement [/b] A cyclist is riding on a path modeled by f(x)= 0.08x where f and f(x) are measured in miles. Find the rate of change in elevation when x = 2 Homework Equations (f(∆x + x ) - f(x))/∆x ∆x\stackrel{lim}{\rightarrow} 0 The Attempt at a Solution I...

Everybody knows what a wheatstone bridge looks like. R1 and R2 are on top and R3 and R4 are on bottom and R5 is in the middle of the angled box shape. let's replace R1 and R2 with 2 different capacitors. Let's also replace R5 with a switch. How would you figure out the potential...

I will be beginning my engineering degree in the fall and I am wondering what specific areas of my high school science courses should I review. What will be the most important topics anyways I won't be blowing off my summer to study but I would feel much more comfortable if I reviewed the...

Hello, I will be beginning my engineering degree in the autumn of 2009 and am wondering if any of the wise men/woman of this forum could give me some advice on how I should prepare myself. I have the motivation but I am slightly intimidated by what appears to me like a pretty heavy course load...

Is chaotic inflation eternal into the past forever, as well as into the future forever. In the theory was there a beginning to it, or has it always been?

Recently, I seem to have been stricken by a learning bug. I have just been craving knowledge of all sorts. I currently am not in college, and it has been several years since I took a math class. I had Intro to Astronomy last semester, and that was pretty decent. However, I currently am wanting...

Hello again guys. The summer is coming up and for most of my friends this means sitting around and eating Haagen Das. For myself, though, I'd like to keep up with what I learned this year so I can avoid that really uncomfortable first two months of school where you're rushing to relearn...

Hey everyone, I was hoping if any experienced astronomers could help me out here. I'm looking to buy my first telescope, my main interest is in observing the planets, the moon, I don't know if this is too much or not, but I would maybe want to see some moons of the other planets and maybe get a...

I'm a high school senior planning on majoring in computer engineering. In my spare time I would like to get a head start on programming. What language should I learn that would best prepare me for what I might be exposed to? My guess is C++ or Java, but I'm not sure. I'm also looking for book...

Homework Statement Okay, I think I'm finally getting the hang of these antiderivatives. However, I'm still stumbling some on trigonometric functions. Find the antiderivative of f(\theta) \ = \ \frac{1 + \cos^2{\theta}}{\cos^2{\theta}} Homework Equations f(\theta) \ = \ \frac{1 +...

Homework Statement Find the antiderivative of F(x) \ = \ \sqrt{\frac{5}{x}} Homework Equations F(x) \ = \ \sqrt{\frac{5}{x}} The Attempt at a Solution 1.) F(x) \ = \ \sqrt{\frac{5}{x}} 2.) F(x) \ = \ (\frac{5}{x})^\frac{1}{2} 3.) F(x) \ = \ \frac{5^\frac{1}{2}}{x^\frac{1}{2}}...

What are some beginning and endings of emails? i.e Dear John, bla bla Regards, Peter What are others. Any website that lists them?

Hey, For most of us undergraduates, it's that time to start a new semester of school. I was just curious as to what "rituals" you may have found successful in preparing yourself for a new term. Anything related to organizing yourself, overviewing the material in any particular way, talking to...

Physicists have anxiously devised one philosophical interpretation of quantum mechanics after another. http://pawst.com/post/586113-new-scientist-in-the-beginning-was-the-bit" with a macroscopic apparatus in the laboratory, which eliminates all possibilities but one.

Since the present idea is that the known Universe (include dark matter) was once condensed into a tiny singularity; and since this 'exploded' into what we now see, how can we measure time of events? Or describe how 'large' the Universe was at any point in time? In other words, I'll read...

Find an equation for the tangent to the curve at the given point. y=2(sqrt(x)) point- (1,2) Ok so I think I can work most of it then I get stuck. I am not sure how you guys use the codes so I will try to type it out the best I can. lim = ( f(a+h)-f(a) ) / (h) h->0 = f(1+h)-f(1) / h...

Please help with this problem. I don't understand how you can know a quantity of rainfall over the given city area just by knowing 1.1 cm. The problem: A heavy rainstorm dumps 1.1 cm of rain on a city 5 km wide and 9 km long in a 2-h period. (a)How many metric tons (1 metric ton = 10^3 kg) of...

What is a good beginning computer language? Also, do projects such as the ones on makezine.com require a proprietary language for their own hardware? Thanks

this place is neat i have some friends on this site and they said nobody will pick on me here I am quiet and listen. i joined elsewhere and they told me i was a newbie and posted in the wrong area sorry guys i am learning. be nice to me and I am sure i can help you somehow thank you im...