Beyond Lorentz force
When a wire is placed in a magnetic field, Lorentz force acts on an electron in a direction perpendicular to velocity and to the magnetic field, since the magnetic force is perpendicular to the...
View ArticleCalculating Electromagnetic Force at 0 Distance?
If you'll allow me to disregard the effects of Strong Interaction, how would I calculate the Electromagnetic Force between two oppositely charged point particles that are in contact with one another?...
View ArticleDisc Magnets
Hey guys, It has been a while since I've done anything to do with magnetism and was wondering if I covered one side of a disc magnet is a non magnetic glue, would this weaken the polarity of this side?...
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Projecting an image back into a slide projector
Hello, I am working on a project in which I want to project a projection back into a slide projector using a concave mirror. Attachment 68797 The lens of the projector has a focal point of 100mm (and...
View ArticleRC Circuit Problem
"A capacitor is being charged from a battery and through a resistor of 20 KOhms. It is observed the the voltage on the capacitor rises from 10% of its final value to 90%, in 15 seconds. Calculate the...
View ArticleWhy is a vacuum sucked toward another object
From the result of an experiment it seems to be that suction does indeed cause a force that causes a vacuum to move toward what is being sucked. Why this is we do not know. Maybe it is related to the...
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Asimov pendulum
I am reading about the Asimov pendulum (see figure) The aceleration in spherical coordinates is ##\vec{a} =( R \dot{\theta}^2 - R \omega^2 \sin ^2 \theta) \hat{r} + (R \ddot{\theta} - R \omega ^2 \sin...
View ArticleCalculating the turning moments for a passive wind turbine under yaw
Hi I have been looking for some simple equations that describe the turning moments on the rotor as wind direction changes. I know this can be relatively complex but I am looking for simplified...
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Sum of forces
Hi, No external gravity here for simplifiy the study please. I try to understand how the sum of forces can be at zero on this study. A container with water inside turn at ω rd/s. The container is not...
View ArticleIdea for a perpetual motion machine
If someone were to send a probe out to interstellar space, bring it to a full stop and start rotating, would it continue rotating eternally? Or would drag from errant plasma slow it?
View ArticleApplication of virial theorem
How do you use the virial theorem to derive the van der Waals equation of state?
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How red glass converts incedent light to red
suppose the white light is incedent on a red glass. Behind the glass we see only red light and glass gets warmer. how exactly white light transformed to red light. Does that mean that the material of...
View ArticleTerminal velocity
I want to estimate how long it will take a person (I could specify their dimensions and density :P but maybe just take it as 170 cm tall, 80 kg, etc.) to fall a certain height in the gravitational...
View ArticleCar Drag Formula Varies with Speed?
Hi, I've read in a website that the drag (air resistance) formula for a car would be different: -> for velocities under 86 km/h Drag = K(coefficient) * V -> for velocities over 86 km/h and under...
View ArticleLinear Velocity vs Uniform Velocity
I was hoping someone could help clarify. Does uniformly increasing velocity also mean linearly increasing velocity? I found terms where it used uniform exponential. So I'm confused as to whether the...
View ArticleIs it electric charge or only the friction?
Hi all, When we rub two stones and get a spark , is there any chance of static charge accumulation or it is just the mechanical energy of friction is transferred in form of heat energy. Thanks in...
View ArticleUniform changing magnetic field does not accelerate a charge?
Consider a charge in free space. There is initially no magnetic field and the only electric field is the one caused by the charge. Now introduce a B field which increases with time:...
View Articlefloor-air convection
I'm trying to do a rough calculation to find the "operating temperature" of a concrete floor. I've found a paper that discusses calculations for rate of heat loss from the slab to the earth: here....
View ArticleTorque Free Rotation....again....
Hello Forum, I have read an old, but good, thread about torque free rotation: http://www.physicsforums.com/showthread.php?t=405781 I am still unclear on how, from the inertial (lab) frame of reference,...
View ArticleStochastic Mechanics (Characteristic functions)
Hi, I reading a book on functional integration, and to develop its methods, the author takes us first through stochastic methods (which I'm guessing in the later parts of the book will lead to...
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