Inertial Definition and 500 Threads

Hello, I've been thinking about inertial and non inertial reference frames. A common example is non rotating reference frame vs a rotating reference frame. As illustration, I have attached two images below. The left is the inertial frame and the right is the non inertial frame. Both...

There is a lot of discussion on this but I still have doubts. Can someone help clarify and point me to correct thread? Object free falls due to gravity (acceleration) so the frame should be non inertial for outside observer. But object does not experience pseudo force in free fall so it may be...

Is there any credible hard evidence that this equivalence extends to all moving bodies? We accept on good grounds that the apparent mass of moving objects is enhanced by motion, to a measurable degree that increases indefinitely as observed speeds of relative motion approach c. Likewise...

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...

Homework Statement The figure shows a rigid assembly of a thin hoop (of mass m = 0.25 kg and radius R = 0.13 m) and a thin radial rod (of length L = 2R and also of mass m = 0.25 kg). The assembly is upright, but we nudge it so that it rotates around a horizontal axis in the plane of the rod and...

I should preface this question by saying that I am not familiar with Einstein's general relativity, so I am trying to understand the relationship between gravitational and inertial mass from a purely classical standpoint. Newton writes that the gravitational force exerted by an object is...

If the speed of light is constant in any inertial frame then how do we measure a red shift or blue shift or why?

When I was surfing on a group in Facebook, I found two concepts very difficult to understand by reading the discussions in comments. Those concepts are inertial and non inertial frame of reference. Please make me understand these two concepts in simple words. Please don't suggest links as I...

Suppose two people separated by some distance, were simultaneously born in an inertial frame that is moving at some velocity with respect to a stationary frame. For an observer in the stationary frame the two events are not simultaneous. The stationary observer will see one person is born...

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! Could someone please explain the difference between gravitational and inertial mass? And how are they equal? Thank you!

Hi, This is not really a homework problem, but a project I'm working on. So, I am trying to build a Simulink model for my quadcopter. I derived the equations of motion using the Newtown-Euler method in the body frame to get transnational and angular acceleration. For the transnational part, I...

In class we had a conceptual problem: There will be a race between two springs. Both will receive the same initial impulse, but one has been agitated and is therefore oscillating in some way, the other is just still. Who arrives first? The answer is that the still spring arrives first because...

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

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...

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...

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...

Homework Statement I am trying to find a local inertial frame for the following metric: ds^2 = -(1+\Phi(x))dt^2 + (1-\Phi(x))dx^2 I can get the transformed metric to equate to η at any point, but I can't get the first derivates wrt the transformed coordinates to vanish. Homework Equations...

Hello, I was wondering about a question and how it would be reconciled within Newton's laws of motion. Take a case where two boxes are stacked on top of each other, and the bottom box rests on a frictionless surface. Now, imagine a rope is attached to the top box, and tension is applied to...

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...

Homework Statement A point P is emitting a bundle of photons. In inertial system I the opening angle of the bundle is d\Omega which hits a plane at a distance R. The same process is being observed by an inertial frame I' moving wrt. I. Show that: R^2d\Omega=R'^2d\Omega' Homework Equations /...

hi, Einstein did not even consider the twin paradox as problematic at all, he argued that it is a simple consequence of his special relativity? obviously he never gave a explanation of why the two twins don't age the same he instead left it to others to do so. was Einstein just having a hunch...

Inertial forces are not real, but apparent forces that are experienced by an observer in a non-inertial reference frame, reflecting the motion of the frame. Thus, you experience a backwards inertial force if you sit in an accelerating car, and a forward intertial force if the break is applied...

Homework Statement Not a homework or coursework question, but given the simplicity of the problem I feel that this is an appropriate subforum. Consider a person spinning a rock on a string above their head at a constant angular velocity, walking away from the observer at a constant linear...

I'm interested in applying inertial navigation over a very small range < 2 meters. Everything I have seen so far that is related to using inertial navigation for dead reckoning is for very large scales and gives accuracy on the order of fractions of miles or several feet. Does anyone know what...

Hi all! I have a question that maybe some people of this great comunity can help. I´m working with a platform with 16 MEMS accelerometers distributed along the whole surface with a knew position and orientation, I have to measure the differences in acceleration on the Z axis, to get the surface...

Hi everyone, I read in a first year textbook (K&K) that the reason why "gravitational mass is proportional to inertial mass" is a big "mystery"... Can someone please explain why this is a mystery? Thanks

I apologize if this has been discussed before. I am no physicist, I am just trying to see if I am understanding special relativity correctly. Please be advised I am dumb, so be gentle. If a spaceship (sorry for the cliché, but it's a little bit cumbersome to keep using the phrase "inertial...

A ball of mass 'm' is inside of a tube that rotates in a horizontal plane around the vertical axis (Drawing a circunference). Attached to the ball (inside of the tube) there is a massless, inextensible rope that goes to the midpoint of the circle described by the rotating tube. The other end of...

I'm wondering if someone is observing a situation from a frame moving in a uniform circular motion, would that frame of reference be considered inertial? I'm unsure because of the centripetal acceleration towards the center.

is it possible by any means to use a type of resonance wave to convert the vibrating motion of molecules in an object such that they start moving in the same direction causing the object to take off at high speed once the majority of the molecules are moving in the same direction? the...

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.

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...

Hi: I'm building a computer simulation for a 3 gear train system. So far the gears rotate with mouse movement horizontally. Now I'm adding a fictitious motor and braking system to start/stop rotation with mouse clicks. I multiplied the rotation angle by [1-e(-t/TC)] to simulate exponential...

Or stated otherwise: Is it possible, due to other effects than mass for a non-spinning object with inertial mass n to exert a gravitational force characteristic of another non-spinning object with inertial mass different than n - theoretically or practically? I hope that covers all the caveats...

How Earth is considered to inertial frame of reference?

Let me set the stage for a thought experiment. 1. A physicist in an elevator at some arbitrary height above Earth holding an accelerometer oriented in a direction pointing toward the center of the Earth. 2. No atmospheric drag. Drop the elevator car and make a measurement. The...

According to Einstein (e.g. in his book The Meaning of Relativity), a clock rotating about a central clock will be judged by the central clock to run slower than the central clock. This means that a signal sent by the central clock will be perceived by the rotating clock as being of a higher...

Hello guys, I just had to ask a quick question about the nature of light. In different synchronization parameters regarding inertial frames (other than 1/2) light can take value between c/2 and infinity. So far, so good for inertial frames. But considering non-inertial frames, what are the...

what is the ratio of inertial mass to gravitational mass and how we can calculate it?

When the 2nd order ODE (ay''+by'+cy=0) is taught, is said that the elastic force is proportional to displacement and that the damping force is proportional to velocity, but I never heard the following proposition: "the inertial force is proportional to acceleration (and the constant of...

Homework Statement Prove inertial force is potential force. Homework Equations $$\mathbf{F}_i=-\nabla V_i$$ The Attempt at a Solution $$\oint \mathbf{F}_i\cdot d\mathbf{r}=0$$

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...

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?

Einstein has a thought experiment with two trains which he uses to prove linear motion without acceleration is inertial. Inertial means there is no physical test which will prove which train is moving and which is stationary, no coordinate system is preferred and that coordinate system are...

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...

Suppose that we have a body that is moving at a straight line, inertially wrt to another frame. If it starts to move in a circular way after that, what can be said about the motions of its points. Do all points have to deccelrate to achieve the circular motion, but in a different manner, since...