# Search results

1. ### Laurent series and partial fractions

Homework Statement find the laurent series of sin(2z)/(z^3) in [z]>0 Homework Equations The Attempt at a Solution I am completely confused. I can understand some of the examples given on laurent series, like using partial fractions and then finding geometric series. Do I rewrite...
2. ### Complex analysis

Homework Statement write f(z)= (z+i)/(z^2+1) in the form w=u(x,y)+iv(x,y) Homework Equations The Attempt at a Solution I tried using the conjugate and also expanding out algebraically but I can not seem to get the right answer. I know what the answer is...
3. ### Laplace inverse

Homework Statement s2/((s2-1)(s-1)2) Homework Equations laplace tables The Attempt at a Solution I attempted the shifting method and also partial fraction method but efforts were fruitless
4. ### Keys are locked

Someone hit some random combination of keys that locked up some of the keyboard. A few of them started working but there is still a couple that don't work. Does anyone know how to unlock these keys?:uhh:
5. ### Simple differential equation

Homework Statement y''+y=5cos(x) Homework Equations y=Acos(x)+Bsin(x) e^ix=cos(x)+isin(x) The Attempt at a Solution I tried using compbinations of these equations to try and solve but i'm lost. Any suggestions would be greatly appreciated!
6. ### Bernoulli in disguise

Homework Statement I think this is a bernoulli equation in disguise (y^7-6x)y'+y=0 Homework Equations I'm having trouble putting it in the form of y'+P(x)y=Q(x)y^n The Attempt at a Solution I've tried to divide out (y^7-6x) as well as some other alebraic manipulation but i keep...
7. ### Gaussian electron cloud

Homework Statement draw the field lines of a simple hydrogen atom model. A case is given where a proton is surrounded by an electron cloud. Without getting into quantum mechanics how would represent the field lines of this mini sphere inside and out. Homework Equations gauss's law The...
8. ### Integrating volumes

Homework Statement Revolve the region bounded by x=0, x=1, y=0 and y=x^5 about the y axis use shells to find the volume I know how to set up the integral I just don't know where i'm integrating from. Is it from 0 to 1?
9. ### Gauss's law help

Homework Statement A hollow spherical conducting shell has a uniformly distributed total surface charge density of -15\muC/m^2. It's outer surface has a radius R1=0.25m. Its inner radius is R2=0.15 m. A point charge, Q= -6.0\muC, is placed at the center of the spherical charge. Determine the...
10. ### Box puzzle

A sheet of material 1000 cm^2 is given to you to construct a box/cube with no lid. What is the maximum volume of the cube that can be created in cm^3?
11. ### Wave equation

[b]1. Homework Statement [/b Determine whether the function D=A sin kx cos \omegat is a solution of the wave equation. Homework Equations D=Asin (kx-\omegat) The Attempt at a Solution sorry completely lost please help Homework Statement Homework Equations The...
12. ### How many hrs do you sleep?

I was curious to see the sleeping patterns of some the intelligent people here at PF. I get 5-6 hrs per night on average. Considering the consensus of a "good night's rest" is 8 hrs, I am worried that my 6 hrs a night might be negatively influencing my studies. What is your sleeping average...
13. ### Graphing polar coordinates

Homework Statement graph the polar function r=2cos\theta (-\pi/2 \leq \theta \leq \pi/2) sorry that last theta/2 should be pi/2. new to this math text Homework Equations The Attempt at a Solution I graphed the positive part right, I think. it seems to trace a half circle. I...
14. ### Can electron spin change?

Can electron spin change? If so how does this happen?
15. ### Energy methods for spring velocity

Homework Statement A spring is attatched to a single position with a 1.2 kg collar at the end. The collar is attatched to a circular fixed body so it can rotate around it. The radius of the circle is 180 mm and the position of where the spring is attatched is 75mm directrly above the center of...
16. ### Very simple tension problem

Homework Statement Two masses are suspended by a frictionless string on a frictionless pulley, one with mass 75 kg and the other 100 kg. What is the tension of the string and the acceleration of the masses The Attempt at a Solution My attempt was to say since mass A, 75 kg, was 75 percent...
17. ### Calculus A,B,C, & D vs. 1,2,3

Im currently taking night courses and all they offer is calculus ABCD. I just finished calc C and the course covered convergent and divergent series, power series, vectors in 3d, and polar coordinates. I was wondering how ABCD compare to 1,2,3? If I complete ABCD does that mean i don't need to...
18. ### Can't find the velocity

Homework Statement This problem arose in my dynamics class. It says that a ball is thrown from a 1.5 m height at an angle of 3 degrees upward. it reaches a wall 6 meters away from where the ball is thrown, and hits the wall at a height of .97 m. The question asks what is the velocity...