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    ODE trouble

    thanks alot for the hit. It was what i needed to solve the problem
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    ODE trouble

    I am having trouble with the following problem: A rocket sled having an initial speed of 150mi/hr is slowed by a channel of water. Assume that, during the braking process, the acceleration a is given by a(v)=-u*v^2, where v is the velocity and u is constant. a) write the equations of...
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    Shortest distance between two points. Line?

    I would like to see the proof that the shortest distance between two points is a line. I found a proof online http://www.instant-analysis.com/Principles/straightline.htm but i can't quite follow it. Does anyone know of a simple proof of this fact?
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    Plasma ball anyone?

    Can someone please explain to me how a plasma ball works? I think I kind of get it. I get that the current flows through the gas inside of the ball because there is a large enough electrical potential difference between the two points. I'm not sure why the sparks follow you finger around the...
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    Dial-up modem and Network card

    i have a dial up modem and a wireless card and so does my brother. They work just fine. and we are able to share my dial up connection. (my machine is xp and has a connection sharing feature build into the operating system). It works just fine. So its possible.
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    Organic light-emitting diode

    has anyone come across any web site with good information on OLED technology. I'm not really looking for the technical details. What I?m interested in is a general overview of the technology. What it is advantage/disadvantages , applications, history. Stuff like that. i would really...
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    Csc x dx

    HallsofIvy lost a negative u= cos(x) so du= -sin(x)dx
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    Integral Problem

    No you are correct , sine is an odd function and integrating it over any interval symmetric about the origin will give you 0.
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    Quantitive Thinking

    I think you just need practice. If it’s a speed problem then practice could help. You say that you would do better if you had more time and that's a problem I can understand, but is it a problem worth solving? I have a similar problem. I am the strongest student in my math class but I take...
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    Solution for this integral!

    for the trig sub x=sin(θ) dx=cos(θ)dθ substitute into original integral simpligy trig expresion and switch limits of integration (evaluate interms of theta) and you will get &pi/4 if you haven't learned trig subs check it out in your calc book it not a very hard topic.
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    Solution for this integral!

    the equation is for a semicircle of radius 1 from 0 to 1 you get a quarter circle and 1/4 pi *r^2=1/4pi 1/4pi is the answer you could also evaluate the integral using a trig subsitution you already found the answer if you devide both sides of the equation by 4 in your solution you also...
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    Math question from the inumerate

    i found my mistake. i evaluated the integral incorrectly. i used a calculator. is there a way to evaluate ∫√(1+cos(x)^2)dx by hand
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    Math question from the inumerate

    You are correct on the interval from 0 to π the length is as you stated but my answer is for [0,2π] I assumed he wanted the length of a single wave which is produce over the interval [0,2π]
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    Math question from the inumerate

    It would go something like this y=sin(x) dl^2=dx^2+dy^2 (Pythagorean theorem applied at the infinitesimal scale where dl is the length of the infinitesimal segment of the curve) dl=√(dx^2+dy^2) dl=√(1+dy^2/dx^2)dx l=∫0…2π √(1+(dy/dx)^2)dx l=∫0…2&pi...
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    A Physics type of integral

    I think I see it now. Thank you both. And Dimitri Terryn I am sorry for saying that you weren't answering my question. I simply misunderstood what you were saying. After reading Hurkyl's answer I realized that you were both saying the same thing.
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    A Physics type of integral

    You answer doesn’t really answer my questing. I was basically asking why the method works, so I guess I was asking for a proof. I have taken Calculus BC in high school which is equivalent to Calculus I & II and I have a book called Thomas’ Calculus that goes through all the way to Calculus...
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    A Physics type of integral

    In my calculus course I was tough to solve differential equations by separation and then integrating For instance dv/dt = a dv = a*dt v= a*t + c (c is a constant of integration) then if I was given an initial condition such as v(0)=Vo I would substitute into my general solution and...
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    Physics 101 lab help should be easy

    I may not be the best person to help you. I just started to learn physics on my own, over summer break. Here goes nothing: I think you use the basic equation for projectile motion. (ignoring air resistance) x = v*cos(10)*t y=v*sin(10)*t – (1/2)*g*t^2 v is the initial velocity and g is...
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    Simple problem for anyone who knows what he is doing

    Thanks, the explanation helped a lot . I think I understand now, but there is still one thing, the force of tension.
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    Simple problem for anyone who knows what he is doing

    I already understood that the mass of the cord hanging down in L2/L. How do you deal with the fact that the horizontal part of the cord is being pulled down and what about the tension in the cord? I don’t understand how all the forces involved effect the system and therefore I don’t...
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    Simple problem for anyone who knows what he is doing

    I’m stuck on a problem involving a cord that has mass. I know how to do problems where the cord's mass is 0 but ones the factor of the cords mass is introduced I’m lost. I’m stuck on the following problem: A block (mass m1) on a smooth horizontal surface, connected by a cord that passes...
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