Reference Definition and 1000 Threads

Uniformly accelerated reference frames in special relativity are represented in the space-like region of a lightcone as hyperbolae. These hyperbolae represent worldline of accelerated observers. However, there could not be be causal relationship between two events on the spacelike section...

So I understand this is probably more contiguous with philosophy than with physics, and there is probably no exact answer to this, but I had a couple of interesting questions relating to planes of reference, keep in mind I am a high school student and possesses very little knowledge of...

What determines whether a frame of reference can be considered stationary? I assume it is not allowed that the Earth be considered stationary and the universe is moving around it for example, as I would have thought that would lead to observation of faster than light movement. In...

Some time in the 1980s when I first started studying relativistic gravity, for ease of comparison with Newtonian and Special Relativity gravity I worked through pages of geodesic equations for a general isotropic coordinate system with spherical symmetry, converting everything to terms relating...

I'm facing a problem in my physics course which is accepting that infinity can be a reference point in both Electrostatics (calculating the voltage of a point) and Matter Properties (calculating the gravitational potential energy), how come we use a reference point which we don't know where it...

I'm not used to Einstein notation and I'm struggling a bit with the more complex examples of it. I got the general gist of it and can follow the basic cases but get sometimes a bit lost when there are a lot of indexes and calculus is involved. All primers I've found online for now only give the...

I know the Galileo invariance don't allow us to take rotational or accelerating frame reference but an shrinking frame reference wouldn't be neither of this. so would be allowed to take an shrinking frame reference?

Hello, I have a question regarding the following picture: Here, person B is moving in his S’ reference frame with a speed of u relative to Person A, who is in his reference frame S. An event shown by a star (*) happens after tA time according to A. The distance of that event is a distance...

1. Homework Statement As shown Homework Equations The answer is A. The Attempt at a Solution Resistance of X = 200^2 / 100 = 400ohm Resistance of Y= 200^2 / 60 = 667 ohm Voltage supply to X= 200 (400)/(400+667) =75V Voltage supply to Y= 200(667)/(400+667)= 125V From the graph ,put 75 V, I get...

I can say that the distance between my knuckle and my finger joint is 1~ inch, that a baseball weighs ~1 lb, and ~60 joules is the feeling of dropping a bowling ball on your foot. I'd like to understand strain in this way, can anyone offer a common place reference? Also, I know strain is...

Hi again, probably this seems to be a simply question, but in last days i becomes a really strange one. We all know that there are many kinds of constants in physics, some of them, are found experimentally with great accuracy in too expensive projects, but no matter how accurate can be measured...

kuruman submitted a new PF Insights post Frames of Reference: A Skateboarder's View Continue reading the Original PF Insights Post.

Suppose I am observing a object in a noninertial frame from a noninertial frame , then what will happen to the forces acting on a object with respect to both the frames, frame of reference (FOR) moving uniform with inertial FOR are themselves inertial frame , does it follow the same with a FOR...

With a velocity dependent equation such as de Broglie's λ=h/mv There's just so many questions, where do I start... In your frame of reference, an electron might be standing still but from an outside frame it could be moving at 0.1c does that mean you'd see different wavelengths? What about when...

Dear Friends, Could you suggest me some good textbooks in the mathematical physics that I can use for both studying and reference? I am currently reading Landau/Lifshitz' trilogy along with couple other books (Weinberg for gravity, Arnold, etc) in different branches of physics, and I need to...

Homework Statement At the roller rink, two 20-kg girls accelerate toward each other until they are each moving at 2.7 m/sin the Earth reference frame. They then collide stomach-to-stomach, grab on to each other, and fall to the floor. A. Calculate the magnitudes of the momentum of each girl...

If yes then imagine what I am going to say... From a source two photons are emmutted symultaniously. If one of the photon had eyes to see what will 'he ' measures the velocity of the other photon which is moving with 'him'? Won't it be zero?!

Newtons first law of motion depends on frame of reference So what are some examples , which shows that in this frame of reference F = 0, but a is not equal to zero or vice versa.

Homework Statement A clock moving at v = (3/5)c reads 12:00 as it passes us in our frame of reference, how far away will it be (in light hours) when it reads 1:00. Homework Equations I denote a prime to mean the reference frame of the clock at rest. I use regular lettering to denote 'our'...

Hello, can someone give an example for an incoherent State --> a formula is here on page 7 : http://quantumcorrelations.weebly.com/uploads/6/6/5/5/6655648/2016_robustnessofcoherencetalk.pdf I know that coherenc is e.g. a superposition of e.g. Spin-Up and Spin-Down [z] or so... But i have no...

Hi, I have created a table using Netbeans. Then i have used properties->model option for table to insert row and to give column names using NetBeans frame work. Now i am trying to create an instance variable of DefaultTableModel in the application class: DefaultTableModel model =...

Guys, I'm keep searching for a WHO standard of Radon of Water in Bq/m3 but I can't find one. Can anyone help me find some references of maximun contamination level of Radon in Water? It may be EPA, or something else too. Thanks a lot

Hi all, Can anyone point me to a quantitative explanation of the geometric multigrid and Vanka smoothers? I found a qualitative article describing the GMG smoother, but it doesn't quantify how much it reduces the cost of a problem. I have found nothing yet on the Vanka smoother except that it...

is there any thing which is at rest with every frame of reference. what if an object experiences this situation.

Think at a cop car with a siren that moves with a velocity Vc, it emits a sound with a velocity C Now think about a person that doesn't move, in front of the cop car, shouldn't he register that the speed of the sound emited is Vs= Vc+ C? According to the galileian equations (true for v <<c...

It's said that, speed of light is same in every frame is reference. Consider an ideal situation, if I'm also moving at the speed of light, will I feel light to be at rest or still at the speed of light itself according to my frame of reference?

Imagine that you are sending photons that are polarized at ##45^\circ##, towards a detector that you are facing (e.g. the detectors's input face is parallel to your device/computer screen right now). The detector's polarization axis is also oriented at ##45^\circ##, so all the photons are...

I want to use a differential amplifier to separate the digital and analog ground portions of a circuit, but am not confident in my understanding of the datasheet of the amps I have on hand (amp03). http://www.analog.com/media/en/technical-documentation/data-sheets/AMP03.pdf I think that...

Hi, I am studying Hypersurfaces and the intrinsic/extrinsic geometry from http://www.blau.itp.unibe.ch/newlecturesGR.pdf with the aim of understanding the Hamiltonian formalism of GR. Although interesting, the notions introduced in these notes lack mathematical rigor. I am looking for a text...

Hi, Can current flow both ways through a NOT gate, or is the diagram I saw, much like the picture I drew here, just drawn the wrong way around? Anyway, say it was correct, so what does this mean? Because the chip itself (the not gate chip Vcc = 5V and Gnd) takes 5V between it and the chip...

why can't speed of light be relative to it's source?

According to special relativity, KE= ([PLAIN]https://upload.wikimedia.org/math/3/3/4/334de1ea38b615839e4ee6b65ee1b103.png-1)(mv^2)/2. Since the velocity measured is dependent on a person's frame of reference, then does that mean energy too is dependent on frame of reference? For example, if an...

Why is speed of light constant in all frames of reference. I don't understand.

I'm trying to get my head around GR. As I understand it, any frame of reference is as valid as any other for modeling the universe. Therefore, it is valid to use a non-rotating Earth as a frame of reference, and try to model the movement that is seen from this frame. But if that is true, I...

I am not certain this is the best place to post this, but not sure General Physics would have been appropriate either. Feel free to move this. I am writing a paper for a quantum physics class, and the professor wants the paper to be in the APS (Physical Review) style. I looked through their...

I want to know why is the measurement of acceleration independent of inertial reference frames? I mean if displacement, velocity varies with change of inertial reference frames, acceleration should vary. And, one more question: When we say that displacement or velocity varies with change in...

Homework Statement Why do objects that have no external net force acting on them accelerate? Ex. If a ball is on an accelerating train, it will accelerate opposite the direction of the train's acceleration, assuming there is nothing blocking its path of motion and it is not strapped down. My...

Homework Statement You are in a car accelerating forwards. There is a baseball at your feet. Draw two FBDs showing the the ball's motion from the frame of reference of the car and the frame of reference of the sidewalk. Which frame of reference is non-inertial? In which frame do you observe the...

Homework Statement Classical Mechanics: John Taylor[/B] (1.27) The hallmark of an inertial reference frame is that any object which is subject to a zero net force will travel in a straight line at a constant speed. To illustrate this, consider the following experiment: I am standing on the...

Special relativity is one of the most tested theories in physics. A central postulated of SR is that the speed of light is the same for all observers in inertial reference frames, and this leads to time dilation and the other effects that have been tested with a high degree of precision. We...

is space an inertial or non inertial frame of reference?

As described in Wikipedia as well as this entry http://physics.stackexchange.com/questions/172739/is-the-lay-explanation-of-the-equivalence-principle-wrong, "being at rest on the surface of the Earth is equivalent to being inside a spaceship (far from any sources of gravity) that is being...

Homework Statement You use a string to suspend a cork ball with a mass of 22.0g from the ceiling of a moving speedboat. The ball and string hang at 32.5 degrees from the vertical. Calculate the acceleration of the speedboat.Homework EquationsThe Attempt at a Solution I was able to calculate...

Hi, so Newton said that gravity was like or equivalent to a force? When I learned about SR we were talking about the passing of time as defined by a photon bouncing between two parallel mirrors. So when we're sitting our two parallel mirrors in a gravitational field, even though I suppose...

Under SR, we can talk about inertial frames that apply globally. However apparently, under GR, this concept only applies locally, because it breaks down on larger scales. Can anyone provide an explanation as to why this is? Is this due to the fact that space-time is warped in GR?

Hello, I wish to know what is the relationship between a frame of reference and time. Specifically,without a frame of reference, what would be a hypothetical state of time. Professor Witten predicts that an ultimate physical theory will dissolve space-time as we know it. I would like to discuss...

Hello all I hope you can help me with this query. I would like to find an introductory text in extra dimensions. I am taking a course in BSM and I have been referred to: C. Csaki, TASI lectures on extra dimensions and branes, hep-ph/0404096, but I was hoping to find something more...

If I am sitting, not moving, my velocity can be zero along with my acceleration but in truth the Earth is moving along with the solar system and so on but i want to know theoretically if a massless object in space can have zero velocity and zero acceleration, in essence what i am askimg is can...

Homework Statement I have seen Earth and ground used interchangeably. However, there appears to be some distinction with regards to reference point ground and Earth ground. My textbook used an example of a loaded voltage divider and examined how the voltage across certain resistors can be...

What kind of frame of reference do I have to choose when I'm studiyng lens and mirrors? As far as I know you consider positive the direction where the rays are real and negative the one where the rays are virtual, is that always true? Why can't we study a problem of optics choosing a frame of...