Symmetry and conservation law
This is my first post, so hello everybody. I don't have university background and english is not my native language, so please forgive me if what I'm writing is hard to understand sometimes. I'll do my...
View ArticleFormula for transverse decrease in signal strength?
Alice is transmitting an electromagnetic beam to Bob. Assume it is a well collimated beam, like a laser beam, or a maser beam. As Bob's distance from Alice increases, his signal strength decreases...
View ArticleWhat things cause drag when moving through a ->uniform
I understand a little about eddy currents and synchrotron radiation; I believe I am correct in saying that they are examples of energy loss (essentially drag) when moving though a gradient of magnetic...
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A strange optics (or math) problem
Hello everyone, I was reading a physics book and found an exercise. This time I faced with a really strange one! I can't find out what I am doing wrong! I am really good at physics and math, but...
View ArticleWhat is the entropy if you have a spray can with 30psi?
I am asking this question because I am trying to understand what entropy is and I just can't seem to get it clear. Now I think the asnwer is 0.5. The pressure of the can is 30. the Atmospheric pressure...
View ArticleWhich should I use to prove this?
(∂s/∂P) at constant volume =1/T ×(∂u/∂T)at constant volume × (∂T/∂P) at constant volume s(P,v) Tds= du +pdv h= u + pv h(P,v) u(P,v) or other formula? How am I going to choose ? Please guide Thank
View Articlewater at 4 degree Celcius has maximum density
During winter why not all the water molecules on the water surface that have 4°C go deep under the water?
View ArticleYoung's double slit angles
I am trying to prove that the two θ are equal from this picture http://en.wikipedia.org/wiki/File:Double_slit.svg How do I go about proving this?
View ArticleJoule free adiabatic expansion dT=0?
In that experiment , the internal energy is zero , volume increase , pressure of system decrease, then temperature will constant ? Thanks
View ArticleDescribing the motion of a linked body?
A general example of a linked body is an object that is made up of rigid bodies joined together by pivots, such as hinges and ball-socket joints. If the pivots are frictionless, and I apply a force to...
View ArticleIf everything has energy... Which "thing" can be an energy source?
Well... If we look at everything in this world,galaxy,universe, We find that every physical object is capable of doing work... If we apply the proper "INPUT" force within a distance in this humongous...
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Moment of Inertia Problem
Here's a derviation from HyperPhysics: He says: [tex]dV=πy^{2}dz[/tex] However, if we're finding the surface area of the sphere: [tex]dA=2πRdz≠2πydz[/tex] If we cannot use [tex]dA=2πydz[/tex], how come...
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Difficulty understanding newtonian mechanics with stationary force
I apologize if this seems much too "freshman", and may come across as annoyingly simple to some more trained or educated on this board. However I will ask the question anyways as I have failed to find...
View ArticleBuckling: Formula to relate Temperature increase with axial Compression
hi, does anyone know how to find how much axial pre-compression is required so that buckling will occur after a temperature rise of 50 C°? I know the cross section of the pinned at each end copper...
View ArticleIs g affected by other sources of gravity?
Earth shouldn't alone make the value of g=9.81m/sec^2. There is the moon, all the planets and our sun (ignoring the outstanding multitude of outer space for my simplicity) and all of these bodies must...
View ArticleFactors affecting speed of travelling waves along a cable
I have a question concerning the speed of propagation of a travelling wave along a cable. If I have a cable and I move one end in a direction perpendicular to that of the length of the cable, it will...
View ArticleThe electromagnetic field in an accelerated frame
Imagine a stationary charge [itex]q[/itex] located on the positive [itex]y[/itex]-axis at a distance [itex]r[/itex] from a stationary observer at the origin. Let us assume that the distance...
View ArticleThe uniqueness of a magnet? Let me tell you why.
In all of the things that we've discovered have you ever found something as amazing like a magnet? An object that can attract/repel (by using force!) on its own similar other magnets or metals. The...
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Could a man hold sustained flight using sound?
I was reading an article on Acoustic Levitation http://science.howstuffworks.com/aco...evitation2.htm and near the end it said Quote: Levitating small objects -- or even small animals -- This got me...
View ArticleDoes logarithmic decrement depend on initial amplitude?
Lets say we have a weight attached to a spring. When releasing it under water (whole motion occours under water) at different initial amplitudes, will logarithmic decrement be the same? And will the...
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