Count Definition and 168 Threads

Hey guys, What method[s] do astronomers use to count the stars in the galaxy to come up with a number ?

Does the new estimate on the number of red dwarf stars in the universe suggest a different proportion of He/H? (current helium abundance estimate is 24%) Would it be lower since more mass would be tied up in low-mass stars (like red dwarfs) in which He/H<0.24.? If not, how many more times should...

What courses count as "upper-division physics?" (also, which GPAs to list) Okay, here is my department's course catalog: http://www.washington.edu/students/crscat/phys.html Anyways, does a "Elementary Mathematical Physics" course count as upper-division physics course? What about a "modern...

Homework Statement [PLAIN]http://img822.imageshack.us/img822/2753/72281206.jpg Yeah...

Hi, I have two majors ,one in Physics and the other is Electronics engineering.I have 7 years of work experience in Embedded systems and firmware development. I want to do MS from a reputed US university( like Stanford ,University of California Berkeley etc). Do you think I stand a good...

The current planet count stands at 490 but can scientists gurantee 100% that they are planets. For instance, isn't it possible to identify a star passing in front of another star (binary) when looking at the light curve?

Homework Statement Find the Uncertainty Measurement using Precision Error and Bias Error? The Length of line is 5.625 in. Precision Error is 0.13 in. Bias Error is -0.115 in. What is the UNCERTAINTY measurement? Homework Equations None. The Attempt at a Solution Please help! I...

Suppose x = 1 2 3 4 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 I need a function to count how many times each set of number occurs eg. 1 2 3 4 occurs 3 times 5 6 7 8 occurs 2 times Thanks!

Homework Statement Count the solutions in nonnegative integers x1,...,xk to x1 + ... + xk=n Homework Equations There's a Theorem in the chapter (shows that the answer is "n+k-1 choose k-1" but we're not allowed to use it. The Attempt at a Solution Well, obviously you can just...

C program help! Hey guys I am having trouble completing this C program. Its suppose to ask the user to enter a file to read from, read the file, count how many times each word appears and print the results in a different file(also user input) arranged from high occurrence. Heres what i...

How to count molecules and determine density, partial pressure and total pressure? Homework Statement Consider three identical boxes each containing a different mixture of O2 and N2. In box #1 are 3 molecules of O2 and 7 molecules of N2. In box #2 are 1 molecule of O2 and 2 molecules of...

Hi I'm a sophomore and I'm barely getting into research now. I plan to do an REU next summer , Junior year, and one after that, Senior year. Do grad schools even get to look at what you did Senior year summer? If so, that would mean we basically only have 3 summers to do research. freshman...

Im reading about T-duality in string theory and I am trying to understand: in a D dimensional, toroidally, compactified space, is there a symmetry for every compact dimension with itself and with every other compact dimension as well? So, I know that T-Duality implies symmetry under R^i...

How is it possible that an amazonian tribe can only count up to five? An Amazonian tribe, the Munduruku, an indigenous group of about 7,000 people whose language has no tenses, no plurals and no words for numbers beyond five. Unfortunately, the copyright on the article has expired...

Suppose I have a gauge potential A_{\mu\nu}, which is totally antisymmetric, if, say, the theory is in 6 dimensions, so that there are 6\times5/2 = 15 degrees of freedom. For the action S = \int d^6x F_{\mu\nu\rho}F^{\mu\nu\rho} , where F_{\mu\nu\rho}\equiv \partial_\mu A_{\nu\rho} +...

The disc in question is {z: |z|<(n+1/2)pi}. I can't figure out how to apply Rouche to this. Any help would be appreciated. (This is in the context of showing all roots of zsin(z)=1 are real. I counted the zeros of zsin(z)-1 on the real axis and got 2n+2, and now I hope to get the same answer...

Hi all! Problem. I have a light source (xenon-arc lamp) and wish to calculate the no. of photons emitted. It seems that I have to use chemical actionmetry (Potassium Ferrioxalate as Chemical Actinometer)? I need to know the no of photons emitted at all wavelengths given out by the lamp at a...

Homework Statement I have John R Taylor "Classical mechanics" part 1, and I have an integral: \int\limits^{x_2}_{x_1}f\left(y+\alpha\eta,y^{\prime}+\alpha\eta^{\prime},x\right)\mbox{d}x and here is count derivative of underintegral function in \alpha \frac{\partial...

Homework Statement after subtracting the bias level from your count, you get a value of (N). to find the noise, you calculate sqrt(N) = noise. now the question, As above, your image has a noise of sqrt(N). What can you say about the presence of a faint star in the image that has a total...

How do I find the total electron count in a transition metal complex? For example, something simple like W(CO)6 or even more complicated like RuH(Cl)(PPh3)3? (Note: I don't mean "d electron count" [which I know how to find], I mean "total electron count.")

Homework Statement I recently was counted off during a math quiz stating that I made a mistake in my arithmetic regarding the derivative of a function using the limit approach. (The long way with the lim h->0) The equation was f(x) = -16x^2 + 20x and I was suppose to find f'(x) using...

How long would it take to count all of the atoms in 12 grams of Carbon-12, If you could only count one atom per second?

Hi, just a quick one, my post count doesn't appear to be updating, it is showing as 10, yet when I click the link on my profile to find all posts by myself it retrieves 96. Anyone else experiencing this / know what the problem is? Why isn't my post count increasing? I'd assume it is a glitch...

This is cool Count every " F" in the following text: FINISHED FILES ARE THE RE SULT OF YEARS OF SCIENTI FIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS... How many?

multiplication and addition principle for count possibilities??/ we toss a fair coin 5 times and recored the sequence of head and tails obtained.how may sequences are possible that start with head OR end with head.? so what i did was using addition theorm i divided this complex process...

What is the best way to put a charge on a plate? By 'plate' I mean some mass of conductor surrounded by an insulator. The problem, really, isn't how to generate charge, I know I can use a Van de graff or high-voltage rectifier for that; the problem is that I need to be certain of how much...

Problem statement:If you have a list, how do you count the Problem statement: If you have a list, how do you count the number of characters in that list? For example, if the list is list=['happy', 'sad', 'angry'], how do I get the program to tell me there are 13 characters in the list...

I have a very basic question related to energy here. We all know that calorie is a measure of energy. Also Energy spent = work done (ignore efficiency) When you walk 1 mile on a treadmill you are doing some amount of work. Based on the above equation you are using up some amount of...

Researchers have found that cell phone signals can alter four essential features of fertile, grade A sperm: 1. Mobility -- How well they move; 2. Viability -- How tough they are; 3. Sperm count -- How many there are; 4. Morphology -- Proper composition. In men who use cell phones, multiple...

hey does anyone know how to do a word count in PDF or Winedt?

Kia gets spliced Saturday, there are people coming from Ireland, Scotland, Wales and England, every thing is planed, i have even finished my speech, now it is all in the lap of the gods, rain is forcast but we will be inside so that makes no difference.

I think I am close but I really cannot figure out how to get the function to work properly. I need to have the user type in several lines and display a count of how many times the word "duck" has been used. I am not sure I am using the strstr right either... any help would be appreciated...

I'm finding the arch length of a curve: $\int_0^b \sqrt{1+sh^2(x/a)} dx$ How do i integrate this function?

I just learned that posts made in the General Discussion forum are not counted in the post count. Does this apply to the sub-sections of GD, like Philosophy? Could anybody tell me the rationale behind this?

Silly to count beyond base 10? If so then you'd have things like '234' as a 'single digit' in base 300 for example. That would be very weird? In the binary system, representing decimals seem like a real pain. i.e 2/3 seems very complicated to represent.

I'm curious as to know how many other PFers you've met in the real world? My tally: 1 (OmCheeto)

Hi, I am am trying to determine the number of rows in a matrix using matlab, I usually use >>[rows,cols]=size(X); >>rows but this requires me to do the operation in 2 steps which will not work in my application. I need to be able to determine the number of rows in one step so I can...

[SOLVED] Count Rate (Quick Clarification) Problem The count rate of a source is 64 counts a second when 50mm away from the source. Assuming the inverse square law is obeyed, what would be the expected count rate when the source is 80mm away. Solution 64 = 50 I know what you mean...

How can I find the number of Rayleighs per count if I know the column emission rate, radiance, irradiance, #photons per pixel and #photoelectrons per pixel? I'm totally lost in this one, please help!

Hi, I want to confirm this: a=8, b=5, c=7 Count out the distance from origo to planet z = ax + by + c in three different ways. 1) With the aid of linear algebra and geometry (no derivates!). Normalvector is: (a,b,-1) , the length * (8,5,1) = p ,(p=point) p=(x,y,z) gives 8s=x ...

I know I should probably have over 1000 by now. I have been in the 850's for 100 posts now. Anyone else have this problem?

I understand that the activity of a source is the number if disintegrations that take place per second in the source. But I do not know how to find the activity from the count rate and time. My question is how do you convert count rate into becquerels? Is there a formula that I can use? Or I...

What is the total number universal physical constants? There are quite a few and some are dependent.

Total program to write number of characters to a file and to read those back. Please help.

Apologies to everyone for being so much an asker an so little a responder, though I would like it noted that I do attempt to answer my questions prior to bothering someone with them. I do a lot of automotive study but as I get deeper and deeper into the subject, the questions just don't seem...

I understand that a massless photon has two polarization states. But I do not understand why a massive spin=1 particle has three polarization states. Can anybody explain? Does the answer depend on the number of spacetime?

Don't cheat! Because if you did, the test would be no fun.I promise, there are no tricks to the test. Read the sentence below and count the F's in that sentence.Count them ONLY ONCE. Do not go back and count them again. See solutions for your score below (it's whited out). FINISHED FILES...

Homework Statement So I was giving a problem to "calculate" the number of flops in class today.. Now, I read the examples in the textbook, and they are hard enough to understand...I am hoping that some one here can push me onto the right track :cool: Homework Equations find the...

Hi I am just having trouble figuring out this question. If someone can help me out it would be greatly appreciated The imaging drum of a photocopier is positively charged to attract negatively charged particles. Near the surface of the drum, its electric field has a magnitude of 1.40 * 10^5...

For the SI measurement sieverts, are they in per seconds ? Off the internet I can find only sieverts measure as "joules per kg" But one of the question in my textbook ask me how much dosage a person is exposed to 3 hrs of 0.3 millisieverts