Stuck — 399 discussions

I'm working on a simple time dilation problem: Astronomers discover a planet orbiting around a star similar to our sun that is 20 LY away. How fast must a rocket ship go if the round trip is to take no longer than 40 years in time for the astronauts aboard? I have set up the problem: T=...

Hey, Got stuck studying complex stuff again, I am trying to find out how i can get rid of the isin2bx in my result, here is the question [PLAIN]http://img832.imageshack.us/img832/3199/unledkcv.jpg The integral of e^(-z^2) = 0 as C is a closed curve and e^(-z^2) is analytic So first...

Let S be a subring of the ring of integers ℤ. Show that if 13 ∈ S and 1000 ∈ S, then S equals ℤ. I'm thinking we should construct a bijection using both numbers. Any ideas? thanks

Homework Statement Evaluate ∫1/x(x-1)2, by using the partial fraction method2. The attempt at a solution Stating in partial fraction form: 1/(x(x-1)2 = A/x + B/(x-1) + C/(x-1)2 1 = Ax(x-1)2/x + Bx(x-1)2/(x-1) + Cx(x-1)2/(x-1)2 1 = A(x-1)2 + Bx(x-1) + Cx and this is where I am stuck...

I am lecturing out of R.Bartle, The Elements of Integration and Lebesgue Measure, for the first time. In the most recent lecture I got stuck not being able to argue an inequality on page 107. I cannot post the text here, sorry. But if anyone has the book, can you also explain how to derive the...

A gas expands according to the equation pv=1000. where p is pressure in kPa and v is specific volume m^3/kg. If the gas pressure drops from 1000 to 500kPa, how much work was done by the gas?? Ok I am new to thermo and given a question and can't figure it out. Do I use net flow work =...

Hi all, I am reading a paper related to astrophysics and I am stuck in a step in a calculation. It is about orbiting gas in a spiral galaxy and it calculates the errors in the fitted rotation velocity if one of the viewing angles is incorrectly estimated. My problem is that I don't understand...

Homework Statement I'm stuck halfway in my differentiation. The question is: Suppose f(x) is the following function when x > 0, find the x-coordinate of the critical point of f(x). Homework Equations Equation = f(x) = e^x - 5x^2 - ln(x) The Attempt at a Solution I solved for...

Hi, I am used to do things independently in my life and rarely takes the advice of others. The one important problem I often face is, whenever I try a method i always stick to it even if it doesn't work. I try to fight with the same approach to find solution to the problem in hand. Though I am...

Homework Statement The gravitational field strength experianced by a satellite orbiting Earth is 4.5 N kg^-1. Calculate how high above the Earths surface the satellite is in orbit. other info: the gravitational constant is 6.67x10^-11 the mass of the Earth is: 6.0x10^24 kg the...

Homework Statement Axler's Linear Algebra done right, propositions 7.6 states: An operator T is normal if and only if ||Tv|| = || T*v||, T* being the adjoint of T. I've been stuck on the last equivalence in the proof stated here: <T*Tv,v>=<TT*v> <=> ||Tv||^2=||T*v||^2, with squaring...

Homework Statement Solve the initial value problem: y'+\frac{4y}{x+8}=(x+8)^{8} , y(0)=8. The differential equation is linear. Homework Equations N/A The Attempt at a Solution I can see that the equation is in the form y' +P(x)*y = Q(x) so I'm like "easy, let me get an...

Homework Statement A crate is stuck in quicksand. The man trying to get the crate out of the quicksand thinks that a force of 2700 N applied in the direction r2 will be sufficient to get the crate free. The crate also has a cable attached to it that is connected to a mechanical crank in the...

1. An antelope moving with constant acceleration covers the distance between two points 70.0 meters apart in 7.00 seconds. It's speed as it passes the second point is 15 m/s. A] Find speed at first point. B] What is the acceleration? 2. From text University Physics 11th edition...

Homework Statement Solve \left | \frac{5}{x + 2} \right | < 1 The Attempt at a Solution All I know is that x= -2 is discontinuous. I thought about doing test points, but it seemed rather useless seeing I will probably end up with (-2, infinity) or (-inf, -2) Computer says the...

use the definition of the derivative to compute the derivative of the function at x=1 f(x) = 1/(1 + x 2) for all x. The Attempt at a Solution i put it into lim[ (f(x)-f(xo))/x-xo ] form and got [(1/1+x2) - (1/2)] <---------numerator ___________________________ <----- division...

Homework Statement Calculate the electric potential due to a tiny dipole whose dipole moment is 6.0×10^−30 C*m at a point 3.6×10^−9 m away for the following cases. a) This point is along the axis of the dipole nearer the positive charge. b) This point is 45 degrees above the axis but...

Hello everyone, This is my first time in Physics forums so forgive me if I stray from the convention for asking questions. Me and a friend are completely stumped on our first assignment for the year and we are not sure where else to turn! Homework Statement A particle of mass m can...

The question is something like this, find the: d/dx of sin-1 (X+a) /b. then evaluate, intergarte of X / (9-4x-x2) 1/2 & intergarte of X2 / (9-4x-x2) 1/2 What i get for the first part is, d/dx of sin-1 (X+a) /b = 1 / ( -X2/b2-2aX/b2-a2+b2/b2)1/2 Then I'm stuck. xD Sorry for the...

This is not a pro creationism question. I can see where people are coming from with it but there is so much that it doesn't cover or explain but it is treated like the holy grail of "where the universe comes from" ideas/theories. I have nothing against Dr. Hawking by any means but something...

I have been trying to solve the inverse Fourier transform: \int_{-\infty}^{\infty}\left[e^{-j2\pi ft_0}e^{j\theta}\right]e^{j2\pi ft}df I know that the Fourier transform pair says e^{-j2\pi ft_0}e^{j\theta} \leftrightarrow \delta(t-t_0) but the extra phase term e^{j\theta} makes...

Homework Statement Determine the Convergence or Divergence of \sum_{n=1}^\infty\left(sin(1/n)\right) Homework Equations limit comparison test The Attempt at a Solution I don't know what to compare this series to, I tried the harmonic series to get sin(1/n)/(1/n) = nsin(1/n) which...

Here's the deal, I got into Applied Sciences degree and now find myself going down a Chemistry major route and doing really badly at it. I cannot move to a Computer Science in my course so I have to transfer. So I can at least have grounds to be awarded a minor. In order to transfer to a...

So let's say a water molecule is stuck between a positive magnetic field and a negative magnetic field ?

Good morning, I've searched about this case in the internet but just found things about asteriods sharing the same orbit as Earth over the sun, but I wonder if an asteroid can get stuck in Earth's orbit like the moon. Thanks!

Homework Statement Two curves are said to be orthogonal if their derivatives are opposite reciprocals at the point where the two curves intersect. Are 2x^2 + y^2 =3 and x= y^2 orthogonal?Homework Equations I'm not entirely sure what to put here, but I think one relevant thing is to say that...

Homework Statement Im doing a question where I have to graphc y = -4 sin x Ok well I got the period and amplitude, so I have the interval of [0, 2pi] Now, in order to plot points, I have to divide the interval into 4 sub intervals. I don't understand how I do that! This is where I...

Homework Statement In an effort to keep me from spending all summer lying on the couch, I recently started reading Michael Spivak's Calculus on Manifolds; while working on problem 1-6 I got stuck on a technical detail and I was wondering if anyone could provide a little insight. Problem 1-6...

In an effort to keep me from spending all summer lying on the couch, I recently started reading Michael Spivak's Calculus on Manifolds; while working on problem 1-6 I got stuck on a technical detail and I was wondering if anyone could provide a little insight. Problem 1-6 says: Let f and g...

x(t) is periodic with T=3. X(k) is FS coeff. X(k)=X(-k) and X(k)=X(k+2) also integral from t=-0.5 to 0.5 of x(t)dt is 1 integral from 0.5 to 1.5 of x(t) dt is 2. Find x(t) ======== i found that the signal x(t) is even and X(0) is 5/3 (if I'm correct) and integral from t=-1.5 to 1.5 of...

Homework Statement Here's the question...use the limit definition to find the derivation of f(x) = x^2-4x Homework Equations does this use the definition of the derivative formula (using Larson, et al 4th edition of Precaclulus graphing with limits...and trying to teach someone what to...

Homework Statement I'm at the last step of an integral but can't seem to get the right answer. Homework Equations After many substitutions I finally have \int^1_0 arctan(w)dw which from wiki is a standard integral, =[w \text{ arctan}(w)-1/2 \text{ ln}|1+w^2|]^1_0 The Attempt at a...

Reduction of Order ODE - Stuck on question! Help Please! The question says that y1= x is a solution to: x^3 y'' + x y' - y = 0 It then says to use y2 = y1 f(x) So I can do it this far and then I just get lost and my notes don't seem to clear anything! I'm just going to say y(2) = y2...

Homework Statement Supposed to take the derivative of: y(x+2) = 9 I think this is one for the chain rule... Am getting stuck with a fraction with exponent at the bottom and that's a no no that I can't get out of... The Attempt at a Solution Attached

In classical mechanics, reduced mass is a way to conveniently take a two body problem and reduce it to a one body problem with an artificial "origin". It simplifies calculations for orbits and angular momentum, etc. I am familiar with the lorentz transform and the γ factor, but am not...

Homework Statement Evaluate \int \frac{1-cos(x)}{x^2} dx given that it exists (The integral is between 0 and Inf, couldn't figure out how to add limits) Homework Equations No idea, looking round, it seems this is related to the Dirichlet Integral but the proof is way beyond the level I'm...

I am going through a given solution to a homework problem and have come to this statement sina cosb/(sina cosb + cosa sinb) - cosa sinb/(sina cosb - cosa sinb) = 1/(1 + tanb/tana) - 1/(1 + tana/tanb) I have looked over every trig identity that I could find but cannot figure out how the...

1) logba + logcb + logac = 1/logab + 1/logbc + 1/logca 2) logrp = q and logqr = p, show logqp = pq 3) if u = log9x, find in terms of u, logx81 4) log5x = 16logx5, solve for x attempt I know the change of base formula logax = logbx/logba, but I'm not sure if/how to apply it in any...

Hi there, I was wondering if you could help me with a quick problem. I should probably know this but for some reason I am getting confused between different points of view: If I wanted to calculate the maximum torque required by a motor shaft to spin a mass at the end of a rod connected...

Help! I'm stuck at work on the last hour of my 12 hours shift! Soooo tired...:zzz:

1. Use the method of Lagrange multipliers to nd the minimum value of the function: f(x,y,z) = xy + 2xz + 2yz subject to the constraint xyz = 32. I understand the method how Lagranges Multipliers is donw done but seem to have got stuck solving the Simultaneous Equations involving the...

Solidworks Assembly is "Stuck" I made an assembly of a few parts, and I mated them how they should. When I move one part, I need the whole device to move around how it would in real life, but this requires a few parts to revolve/spin about different axes, which seems to confuse Solidworks...

Really stuck... computing orthogonal complement? Homework Statement The Attempt at a Solution :cry: I'm really sorry I can't provide much here because I really don't know how to proceed. Could anyone offer a hint to get me started?

i need to work out the integral on a complex curve: i am just stuck with the integral: int[0,2pi]((ie^it)/(e^it +1+i))dt ps. how do you insert latex text? thank you!

I already understand the problem, but am having trouble with the algebra for textbook Fund of Physics Solutions, Halliday, 8e, Ch6 Prob 34. Copied here http://i56.tinypic.com/20uwhw4.jpg I've been staring at this solution to N2L for hours and can't figure out how to go from the top 4 N2L...

Homework Statement i need to find the first and second of derivative of this θ(t) = A exp−λt cos(ωt) with (-lambda*t) being the power of exp in order to substitute into here I(theta) = −μθ(1st deriv of theta) + γθ(2nd deriv of theta) and then prove that λ = −γ/2I Homework...

Hi folks, The attachment is from Sakurai where he's getting started on angular momentum. I don't understand how he gets between the two equations I stuck a ? on. Any hints gratefully appreciated. Adrian.

Hello , I'm in a very sticky situation this semester I have to take computer programming courses and much to my dismay I have no interest at all, there are only 2 options that I can take : take the semester off or continue and "hope" to get a decent mark? What do you think I should do, the...

Homework Statement Find the standard matrix of T T: \mathbb{R}^2 \to \mathbb{R}^2 first performs a horizontal shear tha transforms e2 into e2 - 2e1 (leaving e1) unchanged) and then reflects points through the line x2 = x1 The Attempt at a Solution e_1 = \begin{bmatrix} 1\\ 0...

I decided last semester to change my undergrad major to physics, the problem is, due to financial constrains (read: transfer students get no financial aid) I am kinda stuck in a liberal arts college with an underfunded physics department, actually the sciences in general are all underfunded if...