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1. Electric potential of square loop

Homework Statement There are four uniformly charged rods of linear charge density \lambda and length a, arranged as a square. What is the electric potential a distance z from the center of the square and along the symmetrical axis? The Attempt at a Solution...
2. Argument Theorem - Complex Analysis

Homework Statement Evaluate (1/2ipi)* contour integral of [z^(n-1)] / [(3z^n) - 1 ] dz Homework Equations I would assume you would have to use the Argument Theorem since this problem comes after the proof of the argument theorem in my book. The Attempt at a Solution z^(n-1)...
3. Complex Analysis: Integration

Homework Statement Evaluate the following integral for 0<r<1 by writing \cos\theta = \frac{1}{2}(e^{i\theta} + e^{-i\theta}) reducing the given integral to a complex integral over the unit circle. Evaluate: \displaystyle{\frac{1}{2\pi}\int_0^{2\pi}\frac{1}{1-2r\cos\theta +...
4. Does NaCl dissolve in HCl?

Hi everyone! I just have a quick question. If I took NaCl and put it in a 1.00 M HCl solution, would the NaCl dissolve? Thanks

Homework Statement Hello everyone! How would you solve a quadratic or nth degree congruence? For example how would I solve: (x^2) + 2x -3 = 0 (mod 8 ) The Attempt at a Solution I know this can be written like: (x^2) + 2x = 3 (mod 8 ) but where would I go from here? and...
6. Basis for P2 and Linear Transformation

Hello. I'm having some trouble with this problem. Any help would be greatly appreciated. Homework Statement Consider B= (2x+3, 3x^2 +1, -5x^2 + x-1} a) Prove that B is a basis for P_2 b) Express -x^2 - 2 as a linear combination of the elements of B c) If t: P_2 -> P_2 is a linear...
7. Jobs for astronomers

Hello. I am currently a High School student wanting to peruse a career in astronomy. I was wondering if there are better job opportunities for astronomers and astrophysicists in countries other than the United States? and if so then which countries? Thanks
8. Multiple integraion

Hello everyone! I need some help with the following problems. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2. Use spherical coordinates to find the center of mass of the sphere of radius 7 and centered at the origin in which the density at any point is proportional to the distance of the point...
9. Work and energy

Hello. I need some help with the following problem. There is a cart on an incline and a pulley with a suspended block. Assuming that (the force of friction)= (mu)(N) symbolically show that the coefficient of rolling friction for the car moving down the incline plane with a constant...
10. Force and tension problems without using newton's laws

Hello. I was trying to find a way to solve the tension problems without using Newton’s laws. The problem says: A weight of 200 kg is supported by two wires. Find the magnitude of the tension in each wire. The angle in the top left is 35 and the angle in the top right is 41. I used the law of...
11. Significant figures

If I measured something to be 43.49 centimeters with a meter stick and I wanted to convert that into meters, would it become 0.4349 cm or 0.43 cm?? Thanks
12. Vectors and planes

Hello. I need some help with the following problem: Find the component of u if u is perpendicular to the plane x- 3y + 4z =0 and the magnitude of u is 3. My work: Some vector v is on the plane v = 1i – 3j + 4k so then the dot product of u and v = 0 Now I’m stuck and don’t...
13. Ctrostatics, Gauss’s Law, and Potential

electrostatics, Gauss’s Law, and Potential Hello. I need some help with the following problems. 4. A solid spherical container has a radius of 15 cm. The electric field 30 cm from the center of this sphere has a magnitude of 800 N/C. What is the surface charge density (sigma) on the sphere...
14. Organic Nomenclature and Simple Reactions

Hello. Can someone please check my work and help me with these problems. I'm sorry it is so long. Predict and balance the following organic equation. -------------------------------------------------------- 1. Ethanol (ethyl alcohol) is burned completely in air C2H5OH + 3O2 >...
15. Balancing redox equation

Hello. I have a question on balancing redox equations. I’ve tried to follow the steps in my book but I don’t understand how to do it. Can someone please walk me through one. H2S(g) + NO3{-1}(aq) > NO(g) + S(s) (acidic solution) Now the book says I have to add electrons but how? Thanks
16. One more series

Hello. I need help on these 4 problems. I wrote the problems out and showed my work for numbers 1 and 3. I have no clue how to do numbers 2 and 4. Any help would be greatly appreciated. [img=http://img10.imageshack.us/img10/8426/calcth31tq.th.jpg] Thanks
17. Determine whether the series converges

Hello. The question says: “determine whether the series converges conditionally or absolutely, or diverges. The series they gave me is an alternating series so I used the alternating series test. The alternating series test has 2 parts. The 1st part says the limit as an goes to infinity must be...
18. Use L'Hopital's Rule to evaluate the limit

Hi. Use L'Hopital's Rule to evaluate the limit. lim x-infinity of (lnx) ^(2/x) The answer is 1. I kept taking the derivative but it seemed like I was going around in circles. Any help would be appreciated. Thanks
19. Problems with physics

Hi. I am having a lot of problems understanding physics. I am in AP Physics C right now and I’m failing. It’s like I will never understand the material. What can I do? Has anyone had this problem before? I feel like I’m the only one. I’ve had many tutors but nothing has helped. I’m just...
20. Application of integrals

Hi everyone. I would really appreciate it if someone could check my work. I was really unsure on how to do some of these. I'm sorry it is so long. 1.) Let R denote the region between the curves y=x^-1 and y=x^-2 over the interval 1<= x <= 10. a. Set up an integral for the area of R...
21. Fluid Pressure and Fluid Force in Calculus II

Hi. I need help on how to set up the integral for these problems. 1. A cylindrical gasoline tank is placed so that the axis of the cylinder is horizontal. Find the fluid force on a circular end of the tank if the tank is half full, assuming that the diameter is 3 feet and the gasoline...
22. Why you can't mix x and y components of vectors?

Hi. Does anyone know of a proof that explains why you can't mix x and y components of vectors? For example you know how if you are solving a physics problem you have to break things up into x any y components (eg: velocity). My physics teacher wanted us to find a proof online that explained why...
23. Solve for three variables with only two variables?

Solve for three variables with only two variables?? Hi everyone :smile: . There are 100 people and 100 bushels of grain. Men get 3 bushels, women get 2 bushels, and children get .5 bushels. How many men, women, and children are there and how many bushels do they each get. Find all...
24. 3 free response practice AP problems

Hi everyone. I need some help with these 3 problems. Any help would be appreciated. 4. Let f be the function defined by f(x)= ln(2+ sin x) for pi <= x <= 2pi (a) Find the absolute maximum value and the absolute minimum value of f. Show your analysis that leads to your conclusion...
25. News Should Great Britain abolish its monarchy?

Should the monarchy in Great Britain be abolished? 1. Yes 2. No We were talking about this in my government class and I wanted to know what other people thought. :smile:
26. Why was I banned?

Hello. Sometimes when I try to go 2 this site www.physicsforums.com a message comes up that says, "Sorry. The administrator has banned your IP address. To contact the administrator click here." Why was I banned? It is so weird because in about 10 minutes form now that message is probably...
27. Why does the water shoot up out of the straw at the top

Hi everyone :smile: ! My physics teacher showed us this thing he made and then asked us “why does the water shoot up out of the straw at the top”? No one knew the answer and he did not tell us the answer. And this has been bothering me for almost 2 weeks now (keep reading and it will make more...
28. Frequency and wavelength of a wave

Hi everyone :smile: . If I had a sine wave on a string at one instant of time how come when I reduce the wavelength and frequency by half the graph of the wave does not change. ~Thanks
29. Help with physics wave problem

Hello everyone! I need help with some problems my physics teacher gave us. The problems I did not show any work for are the ones I have no clue how to do. I would just like a hint or something to get me started (I don't want you to do the whole problem for my because I need to know how to do...
30. Lewis Dot Structures

What would the Lewis structure look like for Cl F? Would it look like this: http://img53.exs.cx/my.php?loc=img53&image=dot8pn.png How do you know when there is a triple bond? ~Thanks