Frames Definition and 610 Threads

Leaving Earth at constant acceleration will make time on board go slower. Acceleration will take the ship closer and closer to c Question is: How long will acceleration act on the ship? The time as measured on Earth or on the ship? The final v will be greatly different. Of course, given enough...

Hi, I have a reference device that outputs euler angles, which are angles that relate the sensor body frame to the north east down frame. These angles are called pitch roll and yaw. The sensor is an accelerometer. I know how to get the rotation matrix that will put accelerations from the...

Let's say I'm floating in space in a spaceship, and there are some stars around. Now I turn on powerful spaceship engines. This causes a huge acceleration, which causes the brightness of some stars to increase a lot. (Those stars that are up in the pseudo gravity well become bright) Does tidal...

In a previous thread, the OP asked for answers at the "I" (i.e., undergraduate) level to the following question: S/he received a variety of contradictory answers, and the discussion may have been hindered by attempts to present more sophisticated mathematical ideas as the appropriate level...

According to the postulates of Einstein theory, laws of physics are same in all inertial frame. What about non- inertial frames? Why they can't be same in non-inertial frame?

Homework Statement A car is moving toward north with a speed of 35 km/h. A truck travels toward west with a speed of 42 km/h. Which is the speed of the caravan according to the car's driver? Homework EquationsThe Attempt at a Solution The solution given by the book is 15 m/s with direction...

Homework Statement Consider a frame that is moving with velocity v in the positive x-direction. An observer in this moving frame measures the velocity of the particle in the x- and z-direction, u_x' = 0.9c, u_z'=0 a) What is the maximum velocity of the particle in the y-direction u_y' measured...

In the usual derivation of time dilation in special relativity, we have two frames of reference, A and B, moving relative to each other with velocity v. In A's frame, a light beam is directed vertically upward toward a mirror and reflected vertically back down. In B's frame, the light follows a...

It's perfectly possible to do physics without using the words "frame" or "frame of reference" at all. The modern view of GR is based not on the idea of "frames", but rather on the idea of manifolds. Take your favorite modern text (Caroll and Wald come to mind), and count the number of times...

Electromagnetic field has a density of energy U = ε/2*E2+ μ/2* H2 And a density of momentum, given by the Poynting vector S = E x H For an element of volume dV you have a four vector of energy and momentum which is [E,P] = dV * [U, S] Being E the energy in the element of volume and P the...

Homework Statement Suppose a frame S' is related to S by a boost in the y direction by v. Imagine a wall is at rest in the S' frame along the line y'=-x'. Consider a particle moving in the x'y' plane that strikes the surface and is reflected by the usual law of reflection θ'i=θ'r. Find the...

Hi, I have been studying lorentz force . The book says force experienced by a charge in magnetic field is But velocity is a relative concept . In one frame of reference(inertial frame) I might observe the charge moving with some velocity and in the 2nd frame(inertial too) I might observe the...

I am reading a paper and am stuck on the following snippet. Given two orthonormal frames of vectors ##(\bf n1,n2,n3)## and ##(\bf n'1,n'2,n'3)## we can form two matrices ##N= (\bf n1,n2,n3)## and ##N' =(\bf n'1,n'2,n'3)##. In the case of a rigid body, where the two frames are related via...

There was a post made here https://www.physicsforums.com/threads/length-contraction-and-the-speed-of-light.818301/page-2#post-5138063 by PAllen that describes a way of measuring length contraction of a moving body as seen in the rest frame. I thought this was a great way to visualise length...

Hi all, Say two events happen in the same place according to one observer (1). They are separated in time by 3 years. According to another observer (2) that is moving relative to the first, the events are separated by 5 years. We can calculate, using the invariance of the spacetime interval...

Sorry for the lame question, but I was wondering if someone could help answer the following. I have two synchronised clocks which I place on two different space ships which then accelerate away from me at the same rate and time until they reach a given speed. Ship A then slows down to be at...

After the recent discussion here about the Sagnac effect** I wanted to see if there is any frequency shift if light is sent from one point on a rotating worldline to another a small distance away. It looks like this cannot happen because ##\gamma=dt/d\tau## is the same at every point on the...

Hi All Physics newbie here... Just a quick question regarding Inertial and Non-Inertial Reference Frames. From what I understand: Inertial = One that obeys Newton's Law of Inertia. Moves at constant velocity in one direction Non-Inertial: One that accelerates. Right? So, I read somewhere that...

Hi Folks, I have some misunderstanding how one can add velocities of different coordinate systems. Consider a planet gear rotating about its own axis and also rotating on its carrier so that the so called velocity of the planet gear relative to the carrier is the planet local velocity minus...

I stumbled upon this video: which seems to claim that past present and future exist at the same time due to the fact that observes in different frames would not agree on the order of events. The video claims that there are frames in which Mozart is alive. I don't think that this is correct...

I'm wondering .. if there is an argument could prove that the relative speed of two inertial frames must be the same .

Hello, I have a question regarding the concept of torque and reference frames. Say for example I have a rod of length L and that the rod has it's right side anchored to act as a pivot point. Now let's say that I input a force on the left side of the bar in an upward direction. Assuming that...

Homework Statement This is a diagram from "Structural Analysis" by Aslam Kassimalli while solving frames using slope-deflection method. In the figure, the tangent to the deflected shape at C` is parallel to the original member AC implying that the slope at C is zero. However, later they have...

In analysis of frames, we say that "The members of the frames are axially inextensible". In context of frames with vertical legs, what I understand is that the length of the chord joining the member ends in the displaced condition would be same in the axial direction. However, what does it imply...

While trying to understand how each frame of reference predict that the other is slower, I discovered what seems to be something unsymmetric. It looks as if it is possible to determine that a frame of reference is not one truly standing still. But that's impossible right? I'm really interested...

An accelerating charge radiates light. But in its own frame of reference it is stationary. So it does not emit light. How is this explained? Extreme Example: A charge inside an elevator is falling in a gravitational field. The elevator is lined with a light sensitive sensor that triggers a...

I've attached an image to a conceptual problem I'm having a little trouble understanding. It shows part a, b, c, and d (but d is cut off). a and b are one inertial frame while c and d are another. c and d makes sense, but I'm having a little trouble with a and b. Based on the image for c, there...

I'm reviewing physics after ~30yrs of neglect, starting with Halliday & Resnick (and the internet). Here's what I understand to be standard Newtonian/classical inertial frames: 1. There exists a set of reference frames, called inertial frames, in which mass, time, force, acceleration, etc. are...

Here's a question I cannot seem to comply with my understanding of Quantum Mechanics. The characteristic wavelength of a particle is responsible for diffraction interference fringes, which is part of the wavefunction solution to the schrodinger equation. But the wavelength of a particle is...

Homework Statement The problem I have is not actually so much a physics problem but more of a logical problem. When we look at rulers and any kind of measuring tools, we start from zero. We count the number of intervals instead of the divisions. Suppose we have a video with 7 frames per...

Are the accelaration and forces in different inertial referance frame equal ?

What is the definition of an inertial frame ? I've read that Inertial frames are reference frames in which Newton's first law applies (i.e.bodies subject to zero net external force moves at constant velocity) , however Newton's 1st law itself is only valid under inertial frames. I find it weird...

Hello, I have a few questions about rotation and relative motion. Suppose we transport the proverbial spinning ice skater used to demonstrate conservation of angular momentum to beginning physics students to a universe with only her and two planets. She is now spinning in deep space...

I am posting a diagram directly from textbook of Resnick and Halliday. In second part of the diagram the assumption is that the light will travel with an angle in the direction of the velocity of the moving reference frame. Is that a valid assumption? Won't they have to direct the light beam...

Homework Statement Let S and S' be two inertial frames of reference where S' is moving at a velocity of 0.6c relative to S. When x = x' = 0, t = t' = 0, where t and t' are time of the clocks on S and S' respectively and x and x' are the x-coordinates of the S and S' frames respectively. An...

1.( Everything is in natural units, hbar= 1 , c =1 ) Situation: Frame A is the lab frame. Frame B is moving at velocity ##\beta## away from frame A along the x-axis. At some point a photon is released from the origin in the B frame. The photon makes an angle ##\theta_{B}## with the x'-axis. 2...

Gorini 1971 (reference below) proves a no-go theorem for attempts to extend the Lorentz group to superluminal velocities in n+1 dimensions, for n\ge3. His assumptions are stated in abstruse notation, but he gives the following translation into plainer language: > Axiom: [...] time has a...

I have a 3-pack of related relativity musings I was hoping someone(s) could enlighten me on: 1) Since the reach of gravity is infinite and the universe is homogeneous and isotropic with regards to the distribution of matter, is it fair to say that no object, even those in deep interstellar or...

So I'm a little bummed out about this one, I'd appreciate the help. Apparently the correct answers should be Fcd = 350lb, Fbe = 1531.25lb, or 1.53 kip. Problem can be viewed here: http://i.imgur.com/pK79lVN.png Here's my attempt at solution album: http://imgur.com/a/GQsxJ What can I do? Did I...

I've read that they must be calculated in the same frame , and so to calculate them in the easiest frame.. * So for a collision when I compute the momentum before and after I should do this in the easiest frame. Considering a specific collision where we are computing the minimum energy to...

When a changed body is accelerated in EM field, it is just a macroscopic net effect of multiple interactions of charged particles in that body with the other changed particles outside. When we say "particle accelerator", it is still a simplification, because particle is not being accelerated in...

Homework Statement A water spider maintains an average position on the surface of a stream by darting upstream (against the current), then drifting downstream (with the current) to its original position. The current in the stream is 0.408 m/s relative to the shore, and the water spider darts...

My friend posed a question to me that I was unable to succinctly answer (or answer at all for that matter). So I thought I'd make an account and ask people who know more about this than I do. Ok. So let's assume that Person A starts at Position 1. Person B is at position 2, which is 1 light...

Please see the pictures. In lab frame, we have rockets A and B initially at rest and clocks in sync. When clocks reach certain time T, both A and B accelerate at 45 degrees to up-right direction. There are inertial observers X and Y, which match the velocity x- and y-components that the rockets...

In college physics 1, I think I'm confusing myself on reference frames, and would like for one of you significantly smarter persons to let me know if I'm on the right path with understanding it, and if not, could point me in the right direction :) We're just beginning inertia and momentum in...

Homework Statement Alex is born in a spaceship and Bill is born on Earth just as Alex’s spaceship passes Earth at 0.90c when t=t’=0 (event A). Planet Z is at rest in Bill’s reference frame (x,ct), where it is 45 light-years (ly) away. Alex, whose spaceship is at rest in the frame (x’,ct’)...

Hello everyone :). I'm new here and wasn't sure where to post my physics question so here I am in the homework help section as my question is homework related... The problem I'm having is of very basic nature however I might have some trouble wording it. I understand an event is something that...

SR directly addresses only inertial frames. Can SR be applied to analyze accelerated frames? For example, consider a point on the rim of a rotating disc. I have see an analysis which makes claims by assigning an associated, instantaneous inertial frame comoving with the point at each...

When neglecting gravity and body size, if a body rotating at uniform angular velocity about a central body sends a light signal to the central body, the central body will receive the wavelength as longer by 1/γ. Conversely, if the central body sends a signal to the rotating body, the rotating...

I managed to confuse myself with a simple thought experiment. I have a spaceship that uses mechanical springs loaded with balls for thrust. We start in a reference frame O where the ship isn't moving and fire one spring, which gives the ship a velocity v. Pick a new frame O', moving at v in...