Confusing Definition and 407 Threads

The main problem is when we say a manifold is curved surely this is a relative concept - curved relative to what? I've looked at lots of threads asking similar questions and the answer which keeps coming up is that you can tell if a manifold is curved if you are within that manifold, for...

Find the area of the following region: Inside: r2 = 6 cos 2θ Outside: r = √3 Here's how I've set up the integral. I have to be making a mistake somewhere in the set up, but I can't figure it out. r1 = √3 r2 = (\sqrt{6 cos 2θ}) \frac{Area}{4}= \frac{1}{2}\int\ (\sqrt{6 cos 2θ})^{2}...

ThIS IS NOT A HOMEWORK! I need to know the difference which is why i used simple setups to help ask a question. This helps me in doing more complicated circuits after understanding where a potential drop occurs and when it doesnt

So in a spacecraft with regular air at 1 atm pressure, a hole gets punched in it (depressurizing it). I'm looking for the Exit Velocity of the air at t=0. Using Units: Internal Pressure: Pi = 1 atm = 101300 [kg / m*s2] Air Density: \rho = 1.2 [kg / m3] And Equation: Pi = 0.5 * \rho * (Ve2)...

Homework Statement I have no idea how to start this problem the way the circuit is drawn is super confusing to me. My original thought would be the two 6's are parallel but that is not true. What method should I use? I am more comfortable with voltage nodal/ mesh...

If a racer travels 3.70m in one second. How long does it take for the racer to travel 2(3.70)m? I was expecting 2s as the result but the book suggests square root of 2 to be the answer. I don't know why? Can anyone help me please.

I have just a few more questions regarding index of refractions and reflections... 8. A fly is 10 cm above the surface of a pond. How high above the water does the fly appear to a fish directly below (nair = 1, nwater = 1.333)? (A) 10 cm (B) 7.5 cm (C) 13.3 cm (D) 12.5 cm (E) fish cannot see...

Hi guys, this is so confusing as there are lots of assumption needed (I think). I can't do this even though I got the answer and tried working backwards. A painter in a crate which hangs alongside a building, weighs 1000N.When the painter pulls on the rope, the force he exerts on the floor of...

The quote is from Jake Goldberg's Albert Einstein: the rebel behind relativity: p. 53: "As objects begin to move rapidly through the dimension of space, their movement throught the dimension of time must slow down, because no object can move through space-time faster than the speed of light."...

1. Initially the system of objects shown in the following figures is held motionless. All surfaces, pulley, and wheels are frictionless. At the instant after the system of objects is released, m2 moves vertically downward. Caculate the acceleration of m1, m2 and M, and the tension T in the...

Homework Statement A bungee jumper with a mass of 78kg tied to a 39 m cord jumps off a bridge from a height of 69 m. She falls to 6 .0m above the ground before the chord brings her momentarily to rest. Calculate the impulse exerted on the jumper by the cord as it stretches Homework...

Homework Statement Find the kinetic energy lost Homework Equations The Attempt at a Solution We solved it in class Ek1 = -206 J Ek2 = 10 J Find the energy lost. The answer is was 2.2 * 10^2 J lost This is confusing for me, to find energy lost, we should subtract the...

For my Computer Science assignment I have to hand in a makefile along with my java code. Given that I've got my code complete in Netbeans how do I make a makefile? Also what is a makefile and what is itmeant to do?

Help with this confusing circuit! Using superposition find voltages! The problem is "In the following circuit, find the voltages at A,B, and C. Use or confirm with superposition." I was able to find the current through the top one ohm resistors as .333A (sorry didnt label on my picture)...

It's saying I don't have an 'if' statement for my 'else if' statement, but I do. You can see clearly from this picture that I do.

In my AP Physics B class that I'm teaching, we arrived at Lenz's Law, and had difficulty with Conceptual Example 21-4 (e), located on page 588 of Giancoli's Physics, 6th Ed., which goes like this: A closed conducting circle of wire is lying the plane of the page (or screen), and there is a...

Homework Statement Someone takes a rock and ties it to a string, and then starts swinging the rock around in a vertical circle. The centripetal force should be... Fc = Fg + FtIt's clear that the book sets Ft=0... but why? Can someone explain this?Homework Equations Fc = m * ac ac = v^2/rThe...

Help with this confusing circuit! test tmrw! Find i across resistor. http://imageshack.us/photo/my-images/202/circuitu.jpg/ my teacher lectures to fast and i don't understand the notes i put down. can someone explain this one to me please??

Homework Statement Rolling Motion Theoretically, a=⅔g sin θ suggests a nonlinear relation between a and θ. Since a linear graph is a very convenient method of testing theoretical equations, it is a good idea to first linearize a=⅔g sin θ. A simple way to do this is to assign a as the...

Homework Statement If ADD = 9 BAD = 7 CAD = 8 Find ADA . Homework Equations Algebra The Attempt at a Solution ADDBAD=9*7 BADCAD=56 ADABCC= 56*8/9 B/C = 7/8 I really don't know how to approach this problem, what must I eliminate and how should I do it ?

Homework Statement Homework Equations λ=xd/nl The Attempt at a Solution Im having some difficulty with the variables, is d= lines/m? and n= 27? from the 50 mark to the yellow mark. then x would be 27*(4.35*10^-6) and l would be 100cm=1m ?

Homework Statement Hello all, I'm trying to solve for 3 unknowns x,y,z. We are given these formulas: http://screencast.com/t/Y8QobUXVB3S3 Homework Equations Please see link provided above. The Attempt at a Solution I first rearrage for root(x) then I rearrange equation 2 for root(y), I...

http://en.wikipedia.org/wiki/Nuclear_binding_energy What is nuclear binding energy ? Here are two possible answers according to the Wikipedia page : 1.Nuclear binding energy is the energy required to split a nucleus of an atom into its component parts. 2.Nuclei are made up of protons and...

So I got this wrong in my physics test, the question goes: The original voltage is 230 v and the lightbulbs are marked so said voltage is assumed for them. How much does the voltage need to drop for a 60 watt bulb to start glowing like a 40 watt bulb. I first tried to find the resistance/ohms...

Hi guys, this is the equation of relative velocities in elastic collisions: Va1x-Vb1x = -(Va2x-Vb2x) I know that this means that the relative velocity of A to B before an elastic collision is the same in magnitude but opposite in direction after the collision. However, this applies only in the...

Hi guys! Another question on work done that stumbled me.. If I push an object with a constant 3500N force at a constant velocity since the friction is 3500N as well, what is the work done if the displacement is 5m to the right?? At first look, I would say its 3500*5=17500J? Because that's work...

Hi guys, I'm very confused by a slope question...I've read that for a person with mass m on an inclined frictionless slope, it's normal force perpendicular to the surface is always equal to the y-component of the weight. Why? I'm always thinking that since the person slides down, he can also be...

hello, Please see attached excerpt of a solution to a problem. I do not understand why the result obtained is to second order ? (this is a diffusion equation they say) Please let me know if you would need more info. Thanks,

In Figure, a constant horizontal force Fapp of magnitude 12 N is applied to a uniform solid cylinder by fishing line wrapped around the cylinder. The mass of the cylinder is 10 kg, its radius is 0.10 m, and the cylinder rolls smoothly on the horizontal surface. (a) What is the magnitude of the...

I cannot find a consistent definition of the studentized residual and the RMSEP, because I've noticed that various websites, lecture notes and software packages mix up 1 or 2 definitions along the way to the point that a "compound" definition ends up very different between one reference source...

Homework Statement There isn't an exact problem I'm struggling with, it's one small part of a larger problem, which involves finding the probability protons will penetrate the Coulomb barrier. I'm trying to understand an example in my notes, and the bit that confuses me is attached as an...

Homework Statement A mass at the end of a light rigid rod of length (r) is dropped from a position vertically above the pivot point. What is the tension in the rod when the mass reaches the lowest point of its swing? Homework Equations PEi +KEi = PEf +KEf and maybe also Acen = V^2/r, maybe...

This girl is so confusing! This Is kind of a long story. So right before the school year started, me and this girl talked all the time. I really liked her and she said she liked me. After a few weeks Into the year, I asked her to be my girlfriend. And she said yes! But then she broke up...

So, um, I am getting confused on integration problems where you have to do something with "a constant factor of n". Like, this example... \int\sqrt{1 + e^{4x^{3}}}e^{4x^{3}}x^{2}dx Then the example says to match it to the formula \int u^{n}du Okay... so it does that, but then...

Homework Statement consider the position vector expressed in terms of its cartesian components, r=xiei. Let w=wjej be a fixed vector whose components wj are constants that do not depend on the xi, so that δwj/δxi = 0 Homework Equations I am trying to evaluate ∇((wXr)^2) The...

Homework Statement Find the integral of \int\frac{cos(x)}{1+e^{x}} Homework Equations Given that \frac{1}{1+e^{x}}-\frac{1}{2} is an odd function The Attempt at a Solution I tried integration by parts, with both u = cos(x) and u = 1+e^x, and both only complicated it even...

Homework Statement Image here shows the question: Homework Equations The Attempt at a Solution I thought the answer would be limit = infinity I don't understand how to find the limit to this question.

"A 93kg water skier floating in a lake is pulled from rest to a speed of 13 m/s in a distance of 20m. What is the net force exerted on the skier, assuming his velocity is constant. So I know I have to find the force I'm going to need acceleration, and to find it I'll need to use a kinematic...

I was hoping someone could clarify a step of an example in my calculus textbook. lim x→∞ (√(2*x2+1))/(3*x-5) = lim x→∞ (√(2+(1/x2)))/(3-(5/x)), (since √x2=x for x>0) The description for the step says to divide numerator and denominator by x. I understand to divide top and bottom of a...

I have seen some definition like, It is a quantity that is coming from the time translational invariance. or a quantity that should be conserved in some process. But I am not able to understand what exactly energy is? In STR mass even can convert into energy, that also make me so confused...

Confusing Integration Question?? Homework Statement The question is as attached. The Attempt at a Solution I am very confused by the question. Firstly is I(y) a function like (tan-1y) or an operator like ∫y? Then they say I(y) - I(∞) = (∏/2) - tan-1y so I suppose that I(y) is basically just...

I can't understand a statement in a proof in a textbook. I'm going to terminate the proof at the line that I don't understand. Homework Statement Prove that there exists an x \in \mathbb{R} such that x2=2.2. Their proof until line I don't understand For this, we define S:= \{y \in \mathbb{R}...

Can anyone help me simplify the expression \frac{\delta g_{\mu\nu}}{\delta g^{\kappa\lambda}}? I haven't seen a term like this before and I don't know how to proceed. It seems like it might be the product of some kronecker delta's but I'm not sure.

My textbook says that dE-TdS+PdV<0 for all irreversible processes. However, for reversible processes, the author says that dE-TdS+PdV = 0, and in fact this equation can be applied to irreversible processes because E is a state function. I'm confused -- this seems to be a contradiction.

The integral of sec x is ln|sec x + tan x| + c. That's what the internet is telling me. Now, I am having trouble understanding the modulus sign. I understand that the ln operator gives real numbers for positive values of the argument and complex numbers for negative values of the argument...

Homework Statement In the diagram below are two blocks. Block A sitting on top of block B has a mass mA = 10.0 kg and is attached to the wall by massless string. Block B, mass mB = 35.0 kg, is pulled by a force F = 75.0 N. The surface under block B is frictionless. The coefficients of friction...

When I use MATLAB to draw contour and color scale map of an array. The result is weird. my code: the first: b=load('c:\...\b.txt'); contour(b) the second: b=load('c:\...\b.txt'); image(b) The results are very different. I upload the array file and two figures.

In some places I see that poisson bracket of {q_{i},p_{j}} = 1 (if i=j) and other times I see that this same bracket equals to -1. This is very confusing! What to do?

Here is a screenshot of a slide that the professor went over in class (PV = Present Value): http://dl.dropbox.com/u/64325990/ECON%20102/Capture.PNG I think the reason why I don't understand what's going on in the math is because I don't understand the question at all. So the bond pays $100...

Considering U1 and U2 which both follow Uniform (0 , A), then after the transformation of variable, i can find x=(U1+U2)/2 has f(x)=2/A(both my classmates and me get this result). However i am confused that when i integrate x by it range from 0 to A (because U1 and U2 both ranged from 0 to...