non-autonomous system
I want to get some terminology straight. A non-autonomous system is as far as I can understand a system, where the acceleration depends explicitly on time. This again means that the phase trajectory...
View ArticleE and B produced by a stationary currrent
I have a stationary electric current like this: [itex]\vec{I}=I_0\vec{e_z}[/itex] and I have to calculate the electric and magnetic fields from an inertial frame that is moving with velocity...
View ArticleDue spheres
We have a metal sphere of radius R in the space and resistivity p. At a distance d>R from it we have antoher sphere of metal of radius r<<R and charge q. The 2 spheres intially are at rest....
View ArticleOne old problem
http://www.physicsforums.com/showthread.php?t=27021 I saw this problem and I think that is interesting but that have wrong formulation. But I'm not sure so I want to ask you. In renorm group method...
View ArticleNeed a Review of Solenoid Equations and their Derivation
I need a review of solenoid equations, such as equations for bar solenoids, toroidal solenoids, and toroidal solenoids with an air gap within them. I think that somewhere along the line I may have...
View ArticleAdiabatic Availability and Changing States
1) What is adiabatic availability? 2) How can the state of a system change without changing amounts of constituents or without changing parameters? 3) Does anyone really use the concept of "adiabatic...
View Articlenumerical method for finding charge density on a conductor
I'm interested in working out an efficient and precise numerical method to find the charge density on a conductor with an axially symmetric shape that is essentially a deformed sphere. (I have in mind...
View ArticleCan Newton's Laws of Motion be simplified?
I was just thinking, are Newton's laws of motion most fundamental, or can they be reduced to something even simpler?
View ArticleThe meaning of the D'Alembert's Principle
The D'Alembert's Principle states that: [itex] \sum_s [\underline{ F_s^{applied}} - \frac{d}{dt} (\underline{p_s}) ] \cdot \underline{δr_s} = 0 [/itex] s - labels particles That is when [itex] F_s...
View ArticleAccelerationg of rotating mass *along* the axis of rotation
Says Wikipedia: "The moment of inertia is a measure of an object's resistance to any change in its state of rotation". Now consider a rotating mass [itex]m[/itex] that I would like to accelerate along...
View ArticleEuler-Lagrange equations
In this document, how do I get 3.2 on page 12? I assume it is the Euler-Lagrange equation given in 3.1 just rewritten. But how? Many thanks in advance
View ArticleMoment of inertia and force needed to tilt/change axis of rotation
Consider a freely rotating body. Let the axis of rotation be the z-axis. For simplicity assume all the mass of the body is concentrated in the x-y-plane, i.e. the plane in which the body rotates. I...
View Articlerotation around center of mass
I had quite a few posts about this some weeks ago, but I am still not sure about it. My question is about why you can always view the motion of an object as a traslation of the cm and a rotation around...
View ArticlePhoton absorption and momentum recoil
Hi When talking about atoms absorbing a photon, a classical picture is utilized. The intuitive picture often presented is that when an atom absorbs a photon, a recoil of [itex]\hbar k[/itex] is...
View ArticleWhat does the "Centroid" of area under Rate vs Time plot represent?
Does the 'centroid' of the area under a rate vs time plot represent anything? I have a bunch of rate vs time plots and was trying to think of a way to compare them, other than just cumulative volume...
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How do I convert mechanical work into torque on a suspended object
Note: given many questions rg spinning objects, this is NOT related to perpetual motion or other similar dreams Q: How do I convert mechanical work (ie: energy from a battery) into a spinning force...
View Articlereduced volume flow in a hovercraft
I was wondering what will happen to a hovercraft which is designed for a given air film thickness, is. slightly lifted above its air film, will the hovercraft start behaving like an helicopter, which...
View ArticleLagrangian and External Forces
Hi all, Doing some self-study on Lagrangian uses on the internet and I'm getting it pretty well thus far, but I'm just not sure how external forces fit in exactly. Up until now I've only tackled...
View ArticleSmall oscillations
Dear friends, In small oscillation problem of classical mechanics, the generalized force is zero (Eq. (6-1)) of the Goldstein book. The suffix 'i' represent the the particle number or coordinate? In...
View ArticleConservation of Momentum
Two 140-kg satellites collide at an altitude where g=8.7m/s2 and the collision imparts an impulse of 1.8x105N.s to each. If the collision lasts 120 ms, compare the collisional impulse to that imparted...
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