Frame Definition and 1000 Threads

In this example I'd like to know about the output of the transformer. What happens if an electromagnetic transformer is powered by a sine-wave and simultaneously accelerating at non-relativistic speeds? I assume the output will still be a sine-wave but the frequency will change. Is this correct?

I have the following question considering frame dragging: A test mass starting at rest near a rotating mass or with an initial velocity pointing towards the center of the rotating mass will be deflected in such a way that it begins to move around the mass in the rotational direction. This is...

Homework Statement In my reference frame, I see two carts collide. Both cart A and Cart B have a mass of 2 kg. Cart A has initial velocity v= 3 m/s i-hat + 2 m/s j-hat, cart B has initial velocity v= 3 m/s I-hat + 4 m/s j-hat. 12 J are released in the collision. In previous parts of this...

I'm having this discussion with my engineering peers: A ball is sitting on top of a train traveling at, say, 10m/s. The ball has mass of 2kg, for simplicity. The ball's kinetic energy KE relative to ground zero is 1/2 m v^2, or 100J. A person riding on the train picks up the ball and tosses...

Suppose a person is standing in a bus, moving with constant velocity and then driver applied the breaks and the person standing moved forward as if something pushed him from behind Whats the reason behind this Is it because bus has become a non inertial frame and we have to add psuedo forces to...

Consider a specific reference frame (0XYZ) attached to Earth. A point (origin) being selected, coordinates are ascribed along with a vector basis. This reference is non-inertial because it is locked to Earth and the acceleration of Earth is not zero. Suppose upon rising one morning I felt...

Homework Statement Find the acceleration of blocks 1 and 2 in both a non-inertial frame of reference (an observer accelerating with the machine) and an inertial frame of reference (observer at earth) Homework Equations F = ma The Attempt at a SolutionI solved the question successfully...

Hi, in this Landau's extract i note that the total derivative is neglected in 2 places. in the first case i think because it's raised twice, but in the second case?

Homework Statement Suppose I have particles with masses m1 and m2 , both are in freefall: Then , looking at the center of mass coordinates , I know that the sum of momentums of masses m1 and m2 in the center of mass coordinates is equal to zero : P1c + P2c = 0 so now I know that the total...

Howdy folks I have to say up-front, that I am not an ME by trade. My background is in EE. So, I apologize in advance if I accidentally make my question confusing. I need to join a couple of these...

Consider a disc being pulled by a constant force F and it is performing pure rolling. Now, the disc has a certain acceleration, point A has a acceleration in right direction and another centripetal acceleration in vertically upward direction but it has zero instantaneous velocity because of pure...

Hello, I was referring to this thread: https://www.physicsforums.com/threads/accelerating-atwoods-machine-problem.44305/ to solve a problem on accelerating atwood machines in which, naturally, one attempts to find the acceleration of each of the individual masses. Although I now understand how...

Homework Statement I'm using Shankar's Introductory Physics course and I can't get a question out of my head regarding his setup of Relativity. There are two observers, S and S'. Observer S is stationary, while Observer S' is sliding past S (to the right) with velocity u. They agree to set...

Consider a scenario where in one frame R, I have a magnet at rest and a solid slab of charges with an arbitrarily large mass moving at velocity v. The overall acceleration of the slab is trivial, however, the v x B exerted on the slab is divergent, thus compressive/tensile stresses are exerted...

Homework Statement Hi everyone. We were discussing conservation of angular momentum as a consequence of rotational invariance in class. There was one point where we needed to compute the change in a vector A when the coordinate frame is rotated by angle Δ(Φ). Homework Equations The teacher...

This Wikipedia article https://en.m.wikipedia.org/wiki/Relativistic_electromagnetism seems (to me) imply that there is always a frame of reference in which a magnetic field can be rather viewed as an electric field modified by relativistic considerations. Is that always true? That is...

Homework Statement Special relativity: A rod traveling with the relativistic velocity of 0.866c moving towards a garage. The length of the rod is L, that of the garage is L/2. From the reference frame of the garage, we find the value of Lorentz factor = 2 we say that rod would fit inside garage...

Lets assume a FTL drive that works only with respect to CMB rest frame (technobabble probably something about inflation/dark energy). So drive speed would vary depending on whether the ship is moving along CMB peculiar velocity (371 km/s towards constellation Leo), or against it. Would that be...

Hello there, I have a question (two very similar questions) about the time and phase delay between rotating objects. I want to describe two extreme cases here: I would appreciate any helps. Case 1 Imagine two observers (people with telescopes maybe) in space that are standing thousands of...

From the book - Introduction to special relativity, Robert Resnick, I learned that it was assumed at that time that speed of light is c in ether frame. And so, there was a need to find out ether frame. I am assuming that ether frame is an inertial frame . Speed of light in vacuum could have...

If I understand correctly, a massive enough hollow sphere rotating in space will rotate the minkowski spacetime inside the shell such that a pair of balls held together by a string and rotating around their mutual center and at the same angular velocity as the shell will experience no (or at...

Speed of a wave in a string is given by √(τ/μ) . But this speed is with respect to which reference frame? Since, the speed depends on τ and μ( which are independent of reference frame ), I can consider speed of wave independent of reference frame. But this is not so. From experiment, we know...

Person A is in car A and person B is in car B. These people don't know if their car is moving (i.e. there is no scenery and their engines don't vibrate or make noises). Car A is stopped and car B is moving with a velocity v. Person A thinks that car B is moving with a velocity v while person B...

Homework Statement Solve for support reactions of a rigid, rectangular steel frame sitting on rubber pads at the four corners (See attached), when a shear force and a moment is applied at some point on the frame. All the known variables are shown in black while the unknown are in red. It is a...

In the wave equation## \frac {\partial^2 \psi} {\partial x^2}=\frac{1}{v^2}\frac{\partial^2 \psi}{\partial t^2}\tag{1}##, v is the speed of the wave propagation. With respect to which reference frame is this speed measured( in general)?

I wanted to share this updated website. To easily watch YouTube videos, frame by frame, go to http://www.watchframebyframe.com Insert the video link, and you can easily move from frame to frame. This is a major upgrade from www.rowvid.com, by the same people, I think. For example: 1...

Hello everyone. Below are two problems I have been thinking about lately. Let’s consider two cases: we have a spaceship surronded by an utter void - nothing outside which the spaceship’s pilot could refer to. The pilot (in his robotic body, allowing him to withstand enormous G-forces) turns on...

Hello everyone, I have some conceptual problems understanding the rotating frame transformation. Take the center of the Earth as inertial frame's origin and another point in Hawaii as rotating frame's origin. In many lecture notes from internet, or Marion chapter 10. The vector describing the...

Hey Forum I'm hoping someone can help me gain some clarify with this problem. This is related to the trolley design thread i created; however this is a different problem so i thought it best to start a new thread. Hope that's ok. Basically, i want to analyze a basic rigid frame for a 4 wheel...

If we put a toy gyroscope in space, like the ones we all played with as kids with the wheel on the inside of a wire frame, and had nothing to reference it to. (stars, planets, dust, exc.) How could you tell if the inside was spinning or the wire frame??

In the book General Relativity for Mathematicians by Sachs and Wu, an observer is defined as a timelike future pointing worldline and a reference frame is defined as a timelike, future pointing vector field Z. In that sense a reference frame is a collection of observers, since its integral lines...

My apologies if there are some related discussions on this topic in another thread here, but I could not find one specifically addressing this question. Big bang theory, as it currently stands, talks of some extraordinarily precise time measurements; you see numbers like that 10^-37 sec...

S'-frame of reference has uniform angular velocity with respect to the frame S. what is the velocity of light in S frame w.r.t S' ?

What is it useful for? Can it help in creating arc length parameterizations?

If everything is relative to something else, who's frame of reference is actually correct? For example an observer moving at 99.9%c will use the exact same laws of physics we use and determine without any doubt whatsoever that Earth is flat... flat as a pancake! So who's frame of reference is...

The stress-energy tensor of a perfect fluid in its rest frame is: (1) Tij= diag [ρc2, P, P, P] where ρc2 is the energy density and P the pressure of the fluid. If Tij is as stated in eq.(1), the metric tensor gij of the system composed by an indefinitely extended perfect fluid in...

I'm planning to create my own bicycle in the university.It will have carbon fiber frame and as you know, there are some companies which can produce what you've designed in CAD software but I've no idea how much does it cost me to make them to produce a carbon fiber bicycle frame. Do you have...

Homework Statement Let ## \mathbf{r} ## be the position of a point in a rigid body relative to some origin ##O##. Let ##\mathbf{R}## be the position of the centre of mass from that origin. ##\mathbf{r^{*}} = (\mathbf{r}-\mathbf{R})##. ## d\boldsymbol{\phi} ## is the infitesimal vector directed...

Homework Statement Observer O at the origin of a coordinate system is at rest relative to two equidistant space stations located at x=+3.00×10^6km (station A) and x=−3.00×10^6km (station B) on the x axis. In reference frame O, station A sends out a light pulse at t = 0 (event 1) and station B...

There is this debate in car audio forums of this question whether it is better to connect your amp ground to the frame of the car or the battery.. basically they haven't came to a conclusion so I was curious what you guys think... Basically what I mean is that when you hook up an amp in the...

Hello everybody, My question is about change of frame of reference and its consequences on an ordinary function. Let's ##B## a frame of reference that is linked to another one ##B'## through a change of basis matrix ##M##. So, for an equation written in the first basis ##B## as...

Homework Statement A pendulum of length l at the north pole is moving in a circle to the east at an angle \theta to the vertical. It has some period T_E as measured in the rotating Earth frame. The experiment is then repeated except now the pendulum is moving to the west with period T_W...

Homework Statement A particle is accelerated so it has a total energy of 10GeV measured in the accelerator’s rest frame. The particle's momentum is 8GeV/c in the same frame. Calculate... a.) Rest mass of the particle b.) Energy in an inertial frame in which its momentum is 6GeV/c c.) The speed...

Ok I have a really basic question. Say you and I are floating in space and there is a single electron in front of us stationary to our frame of reference. Now I start hopping up and down. I see the electron accelerate up and down from my hopping frame of reference. I see a EM wave be...

Homework Statement I know that when the 80kN act on B , the frame will be dispalced by Δ1 to the right .. When the 40kN act on C , the frame will be displaced Δ2 to the right ... Why the author use Δ1 + Δ2 for C ? Homework EquationsThe Attempt at a Solution Is the author wrong ? I think the...

Homework Statement How do we know that the MBC larger than MCB ? Homework EquationsThe Attempt at a Solution I think MCB is larger than MBC because the moment of P about C is larger ... So to resist moment of P about C , opposite MCB is required... Thus, MCB is larger

Sorry if this is a dupe: An astronaut is in a windowless, sensorless starship that is drifting in an unknown location in space. There is an accelerometer aboard which reads zero. The astronaut turns on his ideal linear propulsion engine for one second, losing a negligible amount of propellant...

good morning Sirs, in my special-relativity texbook i read that, for a generic mass particle system, with respect to a particular frame where the total system linear momentum is zero the mass-energy relation will have a simple, well known and 'satisfactory' form. Well: what is this frame? its...

I was watching one of the documentaries of Brian Greene (Beyond Cosmos). here at (12:00-12:10) he says.The skater spins respect to space. My question is How can space-time can be a referance frame itself ? Is it means we can just pick a coordinate and make it a referance frame ? (Sounds...

Homework Statement You are standing at x = 9.0 km and your assistant is standing at x = 3.0 km. Lightning bolt 1 strikes at x = 0 and lighting Bolt #2 strikes at x = 12.0 km. You see the flash from Bolt #2 at t = 10 μs and the flash from Bolt #1 at t = 50 μs. According to your assistant, were...