Lagrangian: q and q-dot independence
Hello! I've read thousand of explanations about how q and q-dot are considered independent in the Lagrangian treatment of mechanics but I just can't get it. I would really appreciate if someone could...
View ArticleSmall block on a rotating table
Imagine a surface that rotates with frequency f about its center, if we set a small block (or a coin, or any flat object for that matter) on the table, I wanted to calculate the maximum radius that you...
View ArticleDiscontinuity of electric field at surface of a conductor
Hi all, So I've been reviewing for the PGRE at the end of next month (wish me luck, I'm going to need it) and I stumbled across something that confused me in my old textbook. I was reading about the...
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Isotrophy of time?
In Landau's Mechanics he derives the three conservation laws of energy, linera momentum and angular momentum from three principles respectivly: homogeneity of time, homogeneity of space and isotrophy...
View ArticleHow to determine if a semiconductor laser is broken
Hi, I was wondering if someone could tell me what the best way would be to determine if a semiconductor laser is broken using a multimeter? I have a semiconductgor laser that is still emitting but the...
View ArticleMagnitude of acceleration
My prof. made me question what magnitude of acceleration is.. Is it acceleration without direction, i.e -6 m/s/s becomes 6 m/s/s or is it ΔV(speed)/Δt (Sorta like magnitude of acceleration is to...
View ArticleDoubt in Inertial frame of reference
Newton's laws of motions are not applicable in Non-inertial frames of reference which means only mutually accelerated frames of references, My question is how can we apply Newton's laws of motions for...
View ArticleKirchoff's voltage law with coils
There is an idea that Kirchoff's voltage law could not be applied to circuit containing coils like this link. https://www.youtube.com/watch?v=eqjl-qRy71w What makes me confused is that almost all books...
View ArticleWhy doesn't a spinning coin flip over?
As titled: I would be satisfied with a qualitative explanation(pure physical), but it would be nice if someone can also provide the mathematical model. thanks
View ArticleWhat do you think of the terms used in this article?
The article is about something spinning at an incredibly high rate, with a blurb from the scientist saying that the spin rate is so high that the angular acceleration is compared to gravity - which...
View ArticleDetermination of electric field E
Theorem in electromagnetism says if the divergence [itex]\nabla\cdot E[/itex] and the curl [itex]\nabla\times E[/itex] are known, then E is uniquely determined. So my question is, the divergence...
View ArticleWhat Is The Mathematical Relationship Between AC Power And DC Power?
Is there a formula that shows the relationship between AC power and DC power? Something on the lines of, for example: Power of AC ... = Power of DC ... ? Thank you.
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Delta function question
in this equation why does k take on both positive and negative values? isn't k a fixed constant that can only be positive or negative Attached Images Dirac.gif (5.6 KB)
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Computer Vision - Ground plane position based on image point
When given an image of a scene of something like a hallway or road (looking down this hallway or road) a vanishing point can be determined. Also, the points on the image must lie on a certain line in...
View ArticleThe Random Walk
There is a chapter in Feynman Lectures on Physics called The Random Walk(41-4). I understand everything till the paragraph right after equation 41.18. I have no idea what he is trying to say. There is...
View ArticleGibbs Free energy change
In reaction there is a Gibbs Free energy change. I'm still not sure what this means as in my secondary school years we just learned of one component of it which is the enthalpy change. That was simple...
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High temp mini tube heater
Hi Everyone, Hope this is the right section of the forum. I need some help to design a small tube heater for a specific application. I have attached a crude picture to show what i need. The flame needs...
View ArticleTopics in mathematics
For a mathematical methods course, the end of year assignment is to study and present a topic in mathematics of my choice. I'd like to pick something directly related to electrodynamics that will prove...
View ArticleCheck my formulas
For a 2 Body Equation: [tex]x = - \frac{1}{2} \frac{GM}{r^2}cos(\theta) cos(\phi) t^2 +v_x t + x_0[/tex] [tex]y= - \frac{1}{2} \frac{GM}{r^2} sin(\theta) cos(\phi) t^2 +v_y t + y_0[/tex] [tex]z= -...
View ArticleOperating a pneumatic cylinder on hot air
I have a portable compressed air cylinder - pressure 10 kg/cm2 - powering a small reciprocating pneumatic piston/cylinder assembly.To increase the usage time of the system,I want to fit electric air...
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