Frame Definition and 1000 Threads

The attempt is above

That said, my approach was to determine the energies and 3-momenta at the center of momentum reference frame for each particle, with a fixed s, and check it corresponds to each one of the above, but I'm having some trouble proving that, for example, E_A=\frac{s+m^2_A-m^2_B}{2\sqrt{s}}. I've...

Homework Statement A locomotive has broken through the wall of a train station. During the collision, what can be said about the force exerted by the locomotive on the wall? a)The force exerted by the locomotive on the wall was less than the force exerted by the wall on the locomotive. b) The...

This is probably common knowledge to relativity aficionados but at Example 7.3 in this paper: https://www.farmingdale.edu/faculty/peter-nolan/pdf/relativity/Ch07Rel.pdf I was surprised to read the author showing that a ship accelerating at 1g from rest for 1 hour and reaching a speed of...

Hi. If 2 bodies with charge q are in rest then both have electric force ##F_1=\frac{q*q*k_q}{|\vec{r}|^2}##. But in another frame of reference, that is moving with velocity v relative to first frame of reference, they feel both magnetic and electric force...

The equation ##x = x_0 + vt + at^2/2## is derived assuming a constant acceleration ##a##. My question is , from what frame is this path ##x(t)## described? Can I use it from a non inertial frame?

I know this is a basic question, but I haven't understood deeply what a inertial frame of reference is, to be more specific, its relation with the first law of motion.

Homework Statement A high-speed centipede in S’ is 10.0 cm long measured at rest in S’. A butcher in S holds two cleavers (A and B) 9.00 cm apart (measured in S). The centipede runs at such high speed v across a chopping block that the butcher measures the length of the centipede to be 8.00 cm...

What is the rate of expansion of the universe and what is it's acceleration rate of expansion? Exactly? I recall it's about 67km/s at 1 mega parsecs? But then what's the acceleration rate? This exact information I cannot find. If the universe is expanding, and this expanding is accelerating...

Hey PF, I am working on a problem set, and one of the problems is proving that the Christoffel symbols vanish at the origin of the coordinates ##y^{\alpha}## given by the coordinate transformation: $$y^\alpha (x) = x^\alpha - x^\alpha_{(0)} + \frac {1} {2} (x^\mu - x^\mu_{(0)} )(x^\nu -...

This question concerns inertial frames. I am aware that an inertial frame is one that is not accelerating. I am aware of an alternative definition: it is one on which no forces are applied. (Yes, they are the same thing.) I am also aware of the d'Alembert "forces" that appear when a frame is...

1. The problem statement A small coin of mass m is placed on a turntable a distance a from the axis. Imagine that the surface is a little sticky, so the coin does not slide immediately. The turntable (initially at rest) is rotated at constant angular acceleration α, beginning at t=0. a.) Find...

Homework Statement This question is actually two question. We have two hollow frames - one is rectangular and another is triangular. the rectangle is rotated and fixated such that the angles in shape are ##\alpha , \beta = 90 - \alpha## and the angle of triangle is ##\alpha##. We have two balls...

Take some sort of system accelerating with respect to an inertial reference frame: let's take a spherical mass on the end of a string forming a simple pendulum with the ceiling of a car, and allow that car to accelerate uniformly. Could someone share with me how they interpret the concept of a...

I have a ball of mass m that is situated on horizontal plane on the northern Hampshire. I am asked to show that the ball is moving, clockwise, in a manner of r = v / ( 2Ω*sin(λ) ) where v is the ball's velocity, Ω is Earth's angular velocity, and λ is the terrestrial latitude So here's what...

Homework Statement Given the frame shown, determine the internal loadings at D Homework EquationsThe Attempt at a Solution This should be a simple problem...but I cannot see where I am making a mistake. If I approach it by examining the entire structure, I get a wrong answer: ΣFx: Ax +...

Hi here is the situation; There's a spherical particle contained with a MEMS sensor (3D accelerometer and gyroscope) moving down a bed. What we want is to estimate the total kinetic energy of the particle. The total kinetic energy has two parts, translational part and rotational part. for the...

Homework Statement The position of a participle in a fixed inertial frame of reference is given by the vector r = i(x0 + Rcos(Ωt)) +j(Rsin(Ωt))where x0, R and Ω are constants. a) Show that the particle moves in a circle with constant speed Homework Equations F = mv2/r The Attempt at a...

Hi, I have a random array which represents method calls. For instance: [3, 4, 7, 40, 39, ...] meaning that method 0 is called 3 times, method 1 is called 4 times, method 2 is called 7 times, method 3 is called 40 times, method 4 is called 39 times and so on upto n. Now consider a module as a...

Hello all, This post is in reference to a previous homework post, found here: https://www.physicsforums.com/threads/show-that-f-gamma-3-ma.338744/ That thread is closed to further replies. Probably because it's nearly 10 years old. That thread is about deriving relativistic force from the...

Homework Statement 3. (a) If an object's acceleration is zero in one inertial reference frame then is its acceleration zero in all other inertial reference frames? (b) If an object's velocity is zero in one inertial reference frame then is its velocity zero in all other inertial reference...

Homework Statement A particle B is standing still while another one, A, is moving towards it with initial 4-momentum ##(E,p,0,0)##. Calculate the change in particle A's 4-momentum as viewed from the particle B's rest frame, in terms of the initial energy E and the scattering angle ##\theta##...

Homework Statement a) Alice is observing a small ball of mass m in relativistic motion bouncing elastically back and forth between two parallel walls separated by a distance L with speed u. After each collision it reverses direction, thereby creating a clock. What does Alice observe as the...

This must be a basic question. :) Bob and Alice have the same age. So in special relativity Bob leaves Alice and travels at very high speed and when it returns is younger than Alice. Bob's time is dilated and his space is contracted from Alice frame of reference. But now, if I take Bob's frame...

A freely falling body (falling in earth) accelerates with time. However, an object inside the body remains at rest (if it was initially at rest) or moves with a constant velocity if it was initially moving with constant velocity. In other words a frame fixed to the body is an inertial frame...

Imagine two frames one inertial (x,y,z) and the other rotating (x',y',z'), their origins are always coincident. The rotating frame is rotating as seen from the inertial frame with a time-dependent angular velocity ##\boldsymbol{\Omega}(t)=(\Omega_x(t),\Omega_y(t),\Omega_z(t))##. In the rotating...

Hello! The angular velocity in the non-inertial frame of a rotating body of mass m is ##\Omega## and I need to find the force acting on the body (in the non-inertial frame associated with the body). In the book they say (without any derivation, they just state it) that the force is...

Hello everyone, I'm trying to design and build a steel support frame for a freestanding loft of sorts. I'm in the process of building a recording studio with acoustically isolated rooms within a big room. This requires freestanding structures decoupled from everything but the floor. Normally you...

This is first post so bear with me. This might be totally a blue sky thought ( ok it almost assuredly is ). But when reading about the frame dragging near black holes I wondered if this effect might also be seen ( at a far lower intensity ) in the motion of galaxies. Not suggesting that...

Homework Statement [/B]We have to find acceleration produced by 10 kg block on 5 kg block with respect to the ground. Downward acceleration of life is 5m/s-2 Homework Equations f=ma g=10m/s The Attempt at a Solution Effective force at play on 10 kg block: mg- ma...

Moderator's note: offshoot from https://www.physicsforums.com/threads/what-is-frame-dragging.762986/ I am trying to understand time travel and i can understand Tipler Cylinders and the cosmic string theory that assist the possibility of time travel but I was looking at Frame dragging because...

Homework Statement Four equal discs of mass ocuppy the vertices of a square frame made by four rigid bars of length and negligible mass. The frame is at rest on a horizontal table, and it can move with negligible friction. An instantaneous impulse is transmitted to one of the masses, in the...

I have some questions about space, inertia and frame-dragging that I can’t find anywhere on the internet. The papers that I have found that deal with the subject are often couched in advanced mathematics, so that I can’t get an intuitive grasp of the phenomenon. I would appreciate if...

An observer standing on Earth has 4 egg timers (ET) ET1 to ET4. All the ETs are identical. Each ET only has one grain of sand in it and all the grains are identical. When a grain of sand falls thru the neck of ET1 it emits a green flash of light. When the grain of sand hits the base of ET1 it...

I'm creating an animation of free precession of a cuboid in GeoGebra. The axis of rotation is not one of the principal axes (but does go through center of mass). Since it's much easier to find the angular velocity and L in the body frame, I defined the e1, e2 and e3 axes (as opposed to the...

Consider that we have a magnet and a magnetometer (a fluxgate magnetometer with a single coil), standing still as shown in fig 1. In fig 1, the magnetic field measured at the axis z1 of the magnetometer coil is B1. But if everything (magnet, magnetometer and the axes) was rotating together...

Homework Statement Homework Equations***i posted the questions and my free body diagrams below The Attempt at a Solution Hi. I'm trying to analyze this structure particularly at points C and B. when drawing the free body diagram, i notice there would be pin forces on C as well as B. Also...

Hi. If the 4-momentum in SR is given by p = m γ(v) ( 1 , v ) then in the rest frame of a particle the 4-momentum is ( m , 0 , 0 , 0 ) using c=1 units. This uses the fact that because v = 0 then γ(v) = 1. I'm confused about this last sentence. The gamma factor is used for the relative velocity...

Hey, I am interesting in analyzing a bicycle's frame statically from a vertical fall of x metres, this after using the energy principle i get that the force F = mv^2/r, where v = sqrt(2*g*h), r is the deformation of the bicycle at its contact point and m is total mass from the cycle and cyclist...

Imagine such situation: A bus is moving at constant speed, a man is standing on the bus and is not holding to anything - he is simply standing. Now, the bus starts breaking with constant negative acceleration and so the man will change his relative position due to the force of inertia. Now...

If a suspended pendulum bob is accelerated (in a car, for example), if you're in the accelerating frame of reference, you will observe the fictitious force which appears to act on the bob (as you're in the accelerating frame, the bob is not 'moving' so to speak, so to establish equilibrium you...

Homework Statement A mass m is initially at rest. A constant force $F$ (directed to the right) acts on it over a distance d. The increase in kinetic energy is therefore $Fd$. Consider the situation from the point of view of someone moving to the left at speed $V$ . Show explicitly that this...

Homework Statement Imagine that you are flying on an airliner on a long flight to Europe, at a constant speed of 300 m/s. a) You throw a ball towards the back of the plane at 20 m/s. You then shine a beam of light towards the back of the plane. How will these two things-the ball and the...

In STR we measure motion relative to a observer, and the he is rest respect to him. We make coordinates relative to "a rest frame" , that is the observer. In GTR ,all motion are calculated from which frame?

Entangled states are only separable relative to certain basis states. So does that mean that reference frames have importance beyond those in spacetime?

Homework Statement I was re-reading my old Relativity book (by Rindler) and taking a look at some of the problems. He asks: Using a Minkowski diagram to establish the following result: Given two rods of rest lengths ##l_1## and ##l_2 (l_2 < l_1)##, moving along a common line with relativity...

Homework Statement Q) Suppose that F1 = 250 lb , F2 = 90 lb , and M = 500 lb⋅ft . (Figure 1) Specify where the resultant’s line of action intersects member BC, measured from B. Homework EquationsThe Attempt at a Solution Okay, so i am having severe problems with figuring out what i did...

I know this is a naive question that has almost certainly been brought up numerous times before, but my search abilities seem not to be sufficient for finding a good answer, so if anyone just refers me, that would be fine. The question: Special relativity concerns comparisons between pairs of...

Homework Statement Use the relation ##\langle \vec e^a, \vec e_b \rangle = \delta^a_b## and the Leibniz rule to give an expression for the derivative of a dual frame vector ##\frac{\partial \vec e_b}{\partial x^a}## in terms of the connexion components. Homework EquationsThe Attempt at a...

Wiki here: https://en.wikipedia.org/wiki/Frame-dragging Claims that: It sounds strange. What happens if an observer is hovering in equatorial plane of the rotating black hole, few meters above the ergosphere? Now an observer starts to release a chain, very slowly. Wiki claims that a chain will...