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1. ### Bifocul Optics Problem

Homework Statement A woman is wearing bifocals that have one-half of the lens with a power of -1.2 D and the other with a power of 1.8 D. A lens provides her with a far point set at infinity and other will give her a near point of 25 cm. Where are her near point and far point WITHOUT her...
2. ### Funny Astrophysics/Physics Shirts: Ideas Wanted!

okay, so I am making an astrophysics/physics shirt and I want it to be really funny. anyone have any ideas?
3. ### Taking Electrodynamics this semester

I am taking Electrodynamics this semester and we are doing the course with the aid of "david griffith's Intro to electrodynamics" there has been a lot of word that the course is extremely difficult... can anyone tell me ways to prepare for it?

wow thank you so much for telling me this in detail. I appreciate it very much... did you go to graduate school as a physics student? and are telling me from first hand experience?

Hello, I am a undergraduate Physics student and I heard that if you pursue a graduate degree in Physics for grad school (not undergraduate) the department pays your tuition for you? Is this true? I have 5 friends that they have finished undergraduate physics (payed their OWN tuition) but...
6. ### The Geometry of Maps (Help)

Okay... I think I found the solution by using parametric equations (t,0); (1,t); (t,1), (0,t) and plugging them in yields (0,0), (0,0), (t,t), (0,t) which makes it not 1 to 1. So... it gives me the triangle with those vertices. is this correct?
7. ### The Geometry of Maps (Help)

Homework Statement Let D* = [0,1] x [0,1] and define T on D* by T(x*,y*) = (x*y*, x*). Determine the image set D. Is T one-to-one? Homework Equations The Attempt at a Solution Okay... So I know it is not one to one, if you take out the point (x=0) then it is one-to-one, so you...
8. ### Vector Calculus Question (I don't understand)

Okay... so I took your advice. so I thought about what you said so T(u,v) maps u => -u^2 + 4u and v to v so for u [0,1] is the interval... so that means [0, -1+4] = [0,3] for v [0,1] goes to [0,1] [0,3] x [0,1] so that means... it maps the square into a rectangle. But...
9. ### Vector Calculus Question (I don't understand)

Homework Statement Let D* = [0,1]x[0,1] and define T on D* by T(u,v)=(-u^2+4u, v). Find the image D. Is T one-to one Homework Equations The Attempt at a Solution I have no idea... I don't know how to do it. The solution is [0,3] x [0,1]... yes it is one to one. am I supposed...
10. ### Find Absolute Max/Min of f(x,y)=xy^2 w/ Domain x^2+y^2≤4

Can anyone tell me the general procedure in doing the following procedure? f(x,y)=xy^2 with domain x^2+y^2\leq4 Find it's absolute max & absolute min. Okay, here is my thought procedure, tell me what I can fix. So I would basically say, find the partial derivatives with respect to x and y...
11. ### What is Special Relativity and how does it work?

What are the equations that describe simultaneity, and hey don't be afraid to throw some math out there. All though I might not be able to grasp things like the Ricci Curvature just yet, I could still derive the equations for Time Dilation & the Lorentz Contraction, so please show me the math, I...
12. ### Differential Equations WTF?

Okay, so I was sitting in my room wondering about the differential operator D. Like for example, solving the equation y\prime\prime+5y\prime+4y=0 introduce D=\frac{d}{dx} (D^2+5D+4)y=0 so you can solve it by doing D=-4, D=-1 e^-^4^x+e^-^x is the solution But how the hell do you solve...
13. ### What is Special Relativity and how does it work?

Me and my friend Syl consistently talk about Special Relativity and it's effects in nature when electrodynamic bodies move at relativistic speeds. I want to make a discussion. What is Special Relativity? How does it work? How much do we understand?
14. ### Evaluate $\int\int(yx^2-2xy^2)dydx$: Get Help Here!

How do you put in limits on the integral? I don't know how to put the code into LaTex
15. ### Evaluate $\int\int(yx^2-2xy^2)dydx$: Get Help Here!

\int\int(yx^2dydx)-2\int\int(xy^2dydx) \int[\frac{1}{2}y^2x^2]=\int(-2x^2dx)=[\frac{-2}{3}x^3]=\frac{-54}{3} -2\int\int(xy^2dydx)=-2\int[\frac{1}{3}y^3x]=-2(-12)=24=\frac{72}{3} =\frac{72}{3}+\frac{-54}{3}=\frac{18}{3}=6 is this okay?

17. ### Evaluate $\int\int(yx^2-2xy^2)dydx$: Get Help Here!

Okay so I took your advice and split the integral and I got 6, is that the correct answer?
18. ### Evaluate $\int\int(yx^2-2xy^2)dydx$: Get Help Here!

\int\int(yx^2-2xy^2)dydx limits for the first are 0 \longrightarrow 3 limits for the second are -2 \longrightarrow 0 solve! help
19. ### Differential Equation (3)

ok I posted this wrong, i feel stupid 2yy\prime\prime+2xy\prime=0 how do I solve this? give me a hint maybe?
20. ### Differential Equation (3)

could you possibly do it, by using the substitution I posted?
21. ### Differential Equation (3)

How did you get that solution besides canceling things out? Cause, this is like a very annoying class, like what method did you use? Did you use p\equiv{y}\prime
22. ### Differential Equation (3)

Okay, objection 1 makes no sense... but I'll give you you're right for objection 2. Here's what the textbook says for case 1: y\prime=p, y\prime\prime=p\prime\mbox {Dependent variable y missing}
23. ### Differential Equation (3)

Did you consider the y\prime that it's not the same as y
24. ### Why Even Talk About Gravitons Even Existing?

Saying that gravity should be ignored from the quantum level and should only be considered with \geq atomic, doesn't make much sense. Because atoms consist of nuclei and other smaller quantum subatomic particles...which all together work together and has a gravitational interaction, although...
25. ### Differential Equation (3)

Solve the Differential Equation 2yy\prime\prime+2xy\prime=0 set p=y\prime, and then it becomes case 1 in the textbook Can someone please help me solve this? It's a night mare
26. ### Differential Equations (2)

Sorry about that, I wrote that wrong the actual problem is xy\prime+y=e^x^y using the substitution u\equiv(xy)
27. ### Differential Equations (2)

I'm having trouble setting up this solution can anyone give me a hint, or set it up, so I can see if what I'm doing is right? xy\prime=y=e^x^y using the substitution u\equiv(xy)
28. ### Differential Equations

Isn't there a way I can write the equation in terms of only X values?
29. ### Differential Equations

I figured out how to do that integral, the steps are as followed (1) \int\frac{1}{1+\cos(u)} (2) use \cos(u)\equiv1-\cos^2(\frac{u}{2}) and then it simplifies to (3) \frac{1}{2}\sec^2(\frac{u}{2}) which comes out to (4) \frac{1}{2}tan(\frac{x+y}{2})=y
30. ### Differential Equations

Okay, but I still don't know how to find that integral, which is what I'm going to go find out now. In the end I still learn something, even though I got the answer, I need to show my work completely, what's an answer without an explanation? a meaningless number...
31. ### Differential Equations

ok, so I plugged it in and I got the following u\prime-1=\cos(u) what do I do now? should I integrate both sides? and then rewrite u into y and x terms?
32. ### Differential Equations

ok how about this x+y\equiv{u} comes out to be 1+y\prime\equiv{u\prime} and then plug the y\prime into the equation?
33. ### Differential Equations

Okay, but how do I differentiate x+y\equiv{u} ? Do I get 1+y\equiv{u} or do I have to rewrite it as u-x\equiv{y} which then becomes u-1\equiv{y\prime} and where do I plug...
34. ### Differential Equations

Solve the following differential equation y\prime=\cos(x+y) Here introduce the new variable: x+y\equiv{u} Please show steps, or else I won't understand this
35. ### Riemann Zeta Function Z(z)

I was wondering how do you calculate the Riemann value, of a Riemann Zeta Function, for example the riemann zeta function for n = 0, is -1/2, which envolves a bernoulli number (what is a bernoulli number and what roll does it play in the Riemann Zeta Function), can anyone explain that to me...
36. ### How do I find the acceleration of a crate based on weight?

\vec F_{Lorentz}=0
37. ### Why Even Talk About Gravitons Even Existing?

I don't know who said it earlier, I think it was NY-sports but, one of the reasons why gravity should be omitted and separated from The Strong & Electroweak forces was because it has no force field. Well... the thing about that is... the boson fields that the other forces operate in, are...
38. ### Physics Techniques

1. Write down all information in a table. (e.g x=1, y=2, z=3...). 2. Write down the unknown in there as (Q = ?) 3. Write down relevant formula's and formula's that relate to it. 4. Also, it's always good to look at certain variables and think of ways of rewriting it, especially when you get...