Frame Definition and 1000 Threads

The swimmer will move in the direction of resultant of his velocity and velocity of water. Draw the diagram and the try to solve it.

How Earth is considered to inertial frame of reference?

Definition/Summary Often in physics we need to consider frames of reference that are non-inertial (the Earth spinning on its axis for example). We must therefore see how these rotating reference frames relate to an inertial reference frame. Equations \frac{d^2\mathbf{r}}{dt^2} =...

Definition/Summary Einstein's theory of general relativity predicts rotating objects drag spacetime around themselves in a phenomenon referred to as frame-dragging or the Lense-Thirring effect. This effect is also sometimes referred to as Gravitomagnetism- Extract from wikipedia- 'This...

Homework Statement So this isn't a homework problem but I don't know where else I am supposed to post for general help. I am basically trying to understand the derivation for the equation of motion of a particle in a rotating frame. See attachment for derivation and which steps I am stuck on...

Does the existence of the "Axis of Evil" observed by WMAP and Planck mean that there is a special frame of reference in the universe?

Astronauts on a long space journey are playing golf inside their spaceship, which is traveling away from the Earth with speed 0.6c. One of the astronauts hits a drive exactly along the length of the spaceship (in its direction of travel) at speed 0.1c in the frame of the spaceship. What is the...

I was just thinking about this, and from a perspective of an inertial frame, it's easy to see how distances contract, times dilate, simultaneity varies between observer and the speed of light is exactly c in each case. But what about non-inertial frames? In the presence of gravity almost...

According to wikipedia, "The moving magnet and conductor problem", I stopped at the equation shown in the attachment. It said that the curl of the E` ( electric field in the frame of the conductor) is equal to minus of the dot product of the velocity of the conductor and the del multiplied by...

Consider an inertial frame where an electric current is flowing in upward direction, a magnetic field is created and its direction is determined by the right hand rule. In the frame of reference of the electric charges which they are at rest, how can the observer in that frame explains the...

For two-body decay, in the center of mass frame, final particle distribution is, $$ W^*(\cos\theta^*,\phi^*) = \frac{1}{4\pi}(1+\alpha\cos\theta^*) $$ We have the normalization relation , ##\int W^*(\cos\theta^*,\phi^*)d\cos\theta^* d\phi^*=1##. And we also know that in CM frame ##p^*##...

If light has a maximum speed of c, what frame of reference is that speed determined from? For example, if you were to turn on a light bulb moving at a constant rate and measured when the light in every direction got to one light year away from it's source, wouldn't some of it reach that...

I am sure this is not the best description of the problem, so let me know how I can clarify. Say there are 2 coordinate systems, with one orbiting around the other. Call one fixed ƒ and the other rotating ρ. The goal is to find the transform between the two frames. What's known is 1) A...

Homework Statement I have attached the problem as a picture on this post, am really really unsure on how to start! so far the only thing i can think of doing is using this equation (\frac{d^{2}r}{dt^{2}})_{s} = ( \frac{d^{2}r}{dt^{2}})_{s'} + 2ω \times (\frac{dr}{dt})_{s'} + \dot{ω}...

I'm reading Lanczos: 'The variational Principles of Mechanics'. I need help resolving a paradox - which is probably trivial… Lanczos (page 100 Dover edition) introduces a system, S', rotating at angular velocity \vec \Omega about an axis through a fixed point with respect to inertial system...

Hi! I am having trouble with this frame. To make a long story short, I did the problem and got the right answer. The issue is that when I wanted to try solving the problem by exploding the structure into individual members, I couldn't get an answer anymore and it's bothering me because I do not...

Let's say there's an electric current in a neutral loop of wire. Then we change to a frame where the loop is moving. That makes the loop an electric dipole, for us. Then somebody shakes one side of the loop, the positive side for example. Do we observe EM-waves? Here's a picture of the loop...

Why does one particular 'frame of reference' have fictitious forces (like inertia) whilst another one doesn't. I understand the basics, but more interested in 'why' space seems to have magically chosen specific frame to be the 'non inertial frame'. Could space be more absolute than we...

Greetings, I'm having some issues with a problem that I is related, though not identical, to Bell's spaceship paradox (this is not for a homework or anything, it just sort of occurred to me when I was thinking about something else). Consider two particles that are initially at rest in some...

I've researched about it and watched a few videos, but I can't seem to get my head around it. Would saying that "it's a marker that is fixed relative to your position, in which Newton's first law holds" be an accurate way to define it?

[b]1. Hi, The problem: A roof support frame has various leadings on it. The frictionless pin joint at points A has vertical and horizontal reaction forces. The rollers at point B allow free movement in the horizontal direction and has a vertical reaction. a/Calculate The total Horizontal...

Hello! I have a problem in classical mechanics that I'm unable to solve. Any help would be much appreciated since we have a partial exam tomorrow. :( Homework Statement There's a picture of the problem in the attachment A mass m, which is on a light rod (lenght d), is attached to a...

Hi guys. Consider the mean occupation number and specific intensity of the CMB photons in the CMB frame as given by the blackbody formulas: ##\eta = \frac{1}{e^{h\nu/k_{B}T_0} - 1}## and ##I_{\nu} =\frac{2h\nu^3}{e^{h\nu/k_{B}T_0} - 1}## with ##T_0## the thermal bath temperature in the CMB...

So I was told that a pseudo-force acts on a body when its's motion is analysed with respect to a non inertial reference frame. I'm a bit confused. Does that mean the reference frame is accelerating with respect to the body, or with respect to the earth? And why does there have to be any sort of...

I'm working on a group project where we test a bicycle frame on ABAQUS. The test is as follow Where F is a static load. It was suggested for us to consider it as 4G*120kg to simulate a laboratory test. We're having a hard time knowing what is the maximum deflection (or stifness) we should...

Homework Statement Assume that all particles are non-relativistic, that the target X is initially at rest, and that x has kinetic energy Tx in the laboratory frame. Show that the total kinetic energy of the reactants in the centre-of-mass frame is given by T* = μTx/mx, where mx is the...

Hi, I have a faced a research problem where I would need to recover a frame field given its connection forms. More precisely, I begin with an orthonormal frame field (given by data) in \Re^3 written as \mathbf F=\begin{pmatrix}\vec f_1\\\vec f_2\\\vec f_3\end{pmatrix} where \vec...

Lift and Drag...Which frame of reference? Hi, When expressing the Lift and Drag acting on an airplane as: F_{lift}=qSC_L F_{drag}=qSC_D where q is the dynamic pressure, S is the wing ref. area, and C's are the lift and drag coefficient. My question: Some sources, like this one...

Hello again, Two days ago, I started a thread asking about the same question more or less, and I was thinking that the matter was clear now in my mind, because I had made an error in my calculations... Before I begin, I want to admit that my English is not very good, and my exposition to...

Hey guys, as we know the concept of the rest frame is one of the most famous concepts in any kind of relativity, because it must be known in which frame the body is at rest. My question is how do we define a rest frame on a solid object that has atoms vibrating, the body clearly does not have...

Homework Statement A train is moving by a stationary observer, Bob, at 0.8c. An observer standing still in the middle of the train, Alice, measures the distance to each end of train as 9*10^11 m. Two lightning bolts hit each end of the train simultaneously, as seen by the observer at the...

... Three scientists are familiar with Special Relativity and it's rules. The three scientists decide to conduct a Special Relativity experiment. The plan is for two of them to get into two separate rocket ships and pass one another nearly head-on overhead while the third scientist...

Suppose we do a constant Jacobian transformation (which is not Lorentz) of a SR (inertial) frame, by using four linear change of variables equations. This defines an apparent field with a constant metric (which is not the SR metric) in which there is relative acceleration of separation. From...

This paper discusses the Bell spaceship paradox: Petkov, "Accelerating spaceships paradox and physical meaning of length contraction," http://arxiv.org/abs/0903.5128 PF has a FAQ on this paradox: https://www.physicsforums.com/showthread.php?t=742729 My purpose in creating this thread is *not*...

I'm slightly confused as to how we discuss centre of mass frames in nuclear reactions. We have the reaction a(A,B)b. Before the reaction we can transfer to the centre of mass frame v_c = \frac{\sum m_i v_i}{\sum m_i} and note that the total energy before the reaction is E_{CM} =...

Earth has a huge angular velocity regarding its rotation. Now let's imagine that the Earth has the velocity of 400 km/s relative to some inertial frame. What will be the velocity of Earth when we take the rotation into account combined with inertial motion? How do the 2 combine? Thanks in...

Homework Statement Hi, I am having trouble with the following problem and I can't seem to find any examples: I am trying to determine reactions at points A and D of the redundant structure below using the unit load method, there is a 10kN load at the top left point (B), all lengths are...

The attachment provided shows a frame in which a large fan is to be rested on. The fan has a weight of 6,060 kg and the location of the centre of gravity is shown in the attachment. I would like to know how to calculate the loads at each point. Could anyone please provide some help on this problem?

I was reading some posts on one of my previous threads (great discussion there btw) and I red something that I really didn't understand. So the basic premise was that if we have 2 clocks that undergo acceleration on the same level, to that they are mutually at rest, that they will see their...

Homework Statement At t=0 a police officer is located at (0,R) on a circular platform whose radius is R and which rotates around the z axis with constant angular velocity ω. The officer's velocity at that point in time is (ωR ,0). At that time, a bird leaves the center of the platform along the...

There are only two frame moving relative with each other at certain velocity. One frame see the other going right and the other to the left. Isn't it contradict that each see the other time running slow and both are correct? And this isn't the case , where one twin leave Earth and each see...

I thought that one of the features of GRT was to allow for ACCELERATING reference frames. Yet none of my textbooks seem to show any examples of this. Even the Kerr metric, for a rotating black hole or mass, seems to be "inertial" in the translational directions. (1) Is all that correct...

hi everyone. I'm having trouble understanding the concept of proper time in general relativity. suppose we have some metric given by a fixed mass distribution, say schwarzschild or something (it's not important) and a test particle go over some path between two events A and B. if we want...

Why is the frame in galvanometers made if aluminum ??

Homework Statement Assume that the center of mass of the Earth moves with approximately constant velocity with respect to the fixed stars, and that \mathbf{\omega}, the angular velocity of the earth, is constant. Rederive the terrestrial equations of motion...

I've been working on a problem that I can't seem to get started on. Here is how it is posted: Metric of a space is: ds^2 = (1+2\phi^2)dt^2 - (1-2\phi)(dx^2+dy^2+dz^2), where |\phi | << 1 everywhere. Given a point (t_0 , x_0 , y_0, z_0) find a coordinate transformation to a locally...

I've asked this question a few times. This time i have tiny change in the question. Instead of people I'm using stopwatch & i have removed the accelerative frame. If you have any doubts I'll clear it but do not skip the topic. All i want is an answer that can be agreeable for all...

Homework Statement "(a) Draw a quark-flow diagram for the weak decay \pi^{-}\rightarrow\mu^{-}+\overline{\nu_{\mu}} . Explicitly include the appropriate intermediate vector boson. (b) By considering the production of \mu^{-} and \overline{\nu_{\mu}} in the rest frame of the vector boson...

Homework Statement A square metal frame in the vertical plane is hinged at O at its centre as shown in the figure. A bug moves along the rod PN which is at a distance ##l## from the hinge, such that the whole frame is always stationary, even though the frame is free to rotate in the vertical...

What is the best/easiest method I can use to get the deflections of a 5-storey, 3-bay frame subjected to lateral loads only? I've used the Elemental stiffness matrix for two-dimensional frame analysis (giving me a 60 x 60 matrix) but I'm getting the wrong deflection values. I think my procedure...