Recent content by pfreemind

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    Coefficient of static friction.

    So if you set the acceleration to zero what happens? ... You need to slow the block down, so Newton's Law say you have to slow it down. To actually solve this problem, one method you can use is to set up three equations, one for position, one for velocity, and one for acceleration. You've...
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    Drilled hole through earth - Diff EQ w/ Gauss' Law

    You might be better off trying to find the position, [;r;], as a function of time and then differentiating. To do this, use Gauss's Law to find the force acting on the particle as a function of [;r;] and then use Newton's Law: [F=ma=\frac{d^2r}{dt^2}] to get an ordinary differential equation...
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    Linear momentum of particle

    Just evaluate the integral [;\int_{-\infty}^{\infty} dx;]. What do you get? Also, [; <p>= m\frac{d<x>}{dt} ;], so if you can find [;<x>;], you should also be able to find [;<p>;].
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    Two electrons and a paradox?

    Thanks guys! Looks like I've got some reading to do! I also appreciate the hand-waving explanation that there is always some sort of repulsive force caused by the electric fields, though this seems to imply that coulomb's law, ampere's law and/or the magnitude of the charges changes with...
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    Two electrons and a paradox?

    Suppose there are two electrons which are not moving relative to each other. Then in the reference frame of either electron, there is an electrostatic force pushing the two electrons apart, and they will move apart. However, if an observer is in a reference frame moving relative to the...