What is Inertial reference frames: Definition and 41 Discussions
In classical physics and special relativity, an inertial frame of reference is a frame of reference that is not undergoing acceleration. In an inertial frame of reference, a physical object with zero net force acting on it moves with a constant velocity (which might be zero)—or, equivalently, it is a frame of reference in which Newton's first law of motion holds. An inertial frame of reference can be defined in analytical terms as a frame of reference that describes time and space homogeneously, isotropically, and in a time-independent manner. Conceptually, the physics of a system in an inertial frame have no causes external to the system. An inertial frame of reference may also be called an inertial reference frame, inertial frame, Galilean reference frame, or inertial space.All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration. Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and the Lorentz transformation in special relativity). In general relativity, in any region small enough for the curvature of spacetime and tidal forces to be negligible, one can find a set of inertial frames that approximately describe that region.In a non-inertial reference frame in classical physics and special relativity, the physics of a system vary depending on the acceleration of that frame with respect to an inertial frame, and the usual physical forces must be supplemented by fictitious forces. In contrast, systems in general relativity don't have external causes, because of the principle of geodesic motion. In classical physics, for example, a ball dropped towards the ground does not go exactly straight down because the Earth is rotating, which means the frame of reference of an observer on Earth is not inertial. The physics must account for the Coriolis effect—in this case thought of as a force—to predict the horizontal motion. Another example of such a fictitious force associated with rotating reference frames is the centrifugal effect, or centrifugal force.
Hi, I was thinking about the following.
Suppose we have a geometric mathematical model of spacetime such that there exists a global map ##(t,x_1,x_2,x_3)## in which the metric tensor is in the form $$ds^2 = c^2dt^2 - (dx_1)^2 + (dx_2)^2 + (dx_3)^2$$ i.e. the metric is in Minkowski form...
Although I am not a physicist, I am interested in physics, and recently I've been reading about special relativity. I have a doubt about it, a difficulty I see in the equivalence of all inertial reference frames which I haven't found solved anywhere, and I've thought perhaps you in this Forum...
Hi,
consider the following in the context of classic mechanics and SR.
We know there exist special "frame of reference" according to free objects stay at rest or keep moving with constant uniform velocities. Suppose you single out a such reference frame according to the Newton law of inertia...
I'm reading about the geometry of spacetime in special relativity (ref. Core Principles of Special and General Relativity by Luscombe). Here's the relevant section:
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Minkowski space is a four-dimensional vector space (with points in one-to-one correspondence with those of ##\mathbb{R}^4##)...
I was reading an article about the misconceptions in cosmological horizons and I wanted to clarify an idea.
https://arxiv.org/abs/astro-ph/0310808
In cosmological perspective, is there a global inertial reference frame (maybe CMB) ? Or all inertial frames are defined locally and there is no...
I have a really stupid question.
Suppose I am in a car and the car is going around a loop.
Yes, the Earth is not inertial -- it rotates -- but let me ignore that and, momentarily, designate the Earth as inertial.
Now, we know the frame of the car is not inertial--the car is turning. We...
Homework Statement
Which of these situations describes you observing from an inertial reference frame?
a. you are in the car of a train, seated at a table, and the train suddenly slows down
b. you are in the car of a train, going north, and the train goes around a curve to go west
c. you are in...
One particular form of the equivalence principle states that
The laws of physics for freely falling particles in a gravitational field are locally indistinguishable from those in a uniformly accelerating frame in Minkowski spacetime
My question is, does one arrive at this conclusion from a...
Homework Statement
Classical Mechanics: John Taylor[/B]
(1.27) The hallmark of an inertial reference frame is that any object which is subject to a zero net force will travel in a straight line at a constant speed. To illustrate this, consider the following experiment: I am standing on the...
As described in Wikipedia as well as this entry http://physics.stackexchange.com/questions/172739/is-the-lay-explanation-of-the-equivalence-principle-wrong,
"being at rest on the surface of the Earth is equivalent to being inside a spaceship (far from any sources of gravity) that is being...
Claim: The acceleration (both direction and magnitude) for any object is the same in any inertial reference frame.
Is this claim true? I think it is, but someone mentioned to me that time may be an issue as it's not agreed upon in all inertial reference frames.
I'd appreciate any references...
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...
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...
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...
Hi guys,
I was reading some stuff about general relativity and the first impression is that isn't completely the follow-up to SR. In what I've read it has a different assumption about inertial frames, that they are only significant only locally. What does this really mean and what are the...
Homework Statement
A bug of inertia m_B collides with the windshield of a Mack truck of inertia m_T \gg m_B at an instant when the relative velocity of the two is \boldsymbol v_{BT}.
(a) Express the system momentum in the truck’s reference frame, then transform that expression
to the bug’s...
Hey everyone,
I started reading up on GR a couple of days ago, and I'm somewhat stuck on the concept of a free-falling IRF. I understand that an observer on a free-falling small spaceship would experience the laws of physics in a rather simple form, eliminating the need for a force of gravity...
What is an inertial reference frame?How are positions,velocities and accelerations changed when switching between different inertial reference frames?
r=rx i + ry j + rz k
Inertial reference frame:It is a frame of reference where Newton's laws of motion is valid.No fictitious...
can inertial reference frame ever have "lenght contractions" in 3d or in rest?
hi!
thank you for all answers in this topic in previous threatin same topic. i open this new
thread in same topic but here i try to keep the issue here very short and readable , with no speculation and concentrating...
Hi to all,
I am a new one to this physics forum and i have a doubt regarding Inertial Reference frames.
In an article of IRF, it is given as "There is no absolute inertial reference frame, meaning that there is no state of velocity which is special in the universe."
Can anybody please...
Hello, I am having difficulty understanding the concept of Newton's first law only applying in an inertial reference frame, or a frame that is at constant velocity, however, apparently the 1st law no longer applies if the reference frame is accelerating. Can anyone give me some sort of concrete...
The initial presentation of Newton’s Laws of Motion (NLM) to students often proceeds as follow: 1. The 3 laws are presented, 2. The caveat that the laws are only valid in Inertial Reference Frames (IRFs) is (sheepishly) mentioned, 3. An attempt is made to define an IRF, and 4. Some examples...
The first law of motion says that it takes force to accelerate something.
The second law of motion says that F=ma.
So now my teacher says that the first law is for inertial reference frames, while the second is for non-inertial reference frames.
This really annoys me because I don't...
An inertial frame is one which is not accelerating.
i.e if I'm sitting in an accelerating bus or plane I'm not an inertial observer however if I am in a bus or train traveling at a constant velocity i.e zero acceleration then I am an inertial observer.
One thing Id like to ask here is that...
Dear all,
I'm trying to understand better why gravity makes impossible to physically define an inertial reference frame.
Firstly, we must have an operational procedure that allows us to physically define an inertial reference frame. Secondly, we must show that gravity makes this procedure fail...
Homework Statement
I'm doing a problem in which an ant crawls in a circle on a spinning pottery wheel.
Say I'm looking at the friction which holds the ant in place. It keeps the ant from slipping.
Looking at it in the inertial frame of reference, I know that the centripetal force points...
Homework Statement
An example of an inertial reference frame is:
A. any reference frame that is not accelerating
B. a frame attached to a particle on which there are no forces
C. any reference frame that is at rest
D. a reference frame attached to the center of the universe
E. a reference...
Homework Statement
A clock chimes every hour, on the hour in it's rest frame, is it possible for an observer to measure the time between chimes less than an hour?
Homework Equations
t = \gamma t0
The Attempt at a Solution
I understand that if an observer traveling in the frame S'...
[b]1. Suppose the space time co-ordinates of two events in inertial frame S are as follows:
Event 1:
x1=x0, t1=x0/c y1=z1=0
Event 2:
x2=2x0, t2= x0/2c y2=z2=0
Show that there exists an inertial frame s' in which these events occur at the same time (i.e t1'=t2') and find the value of time...
Homework Statement
I am a bit confused about what are inertial reference frames and what is not. The text states:
"We define an inertial reference frame as a reference frame in which Newton's laws are valid... Accelerating reference frames are not inertial reference frames...
OK, I'm working on a question regarding IRFs, but I seem to be a little confused.
Question:
Observer A is on the ground and Observer B in on a train moving with uniform velocity v wrt the ground. Each observes that a particle of mass m, initially at rest wrt the train, is acted upon by a...
Can someone help clarify this equation from classical dynamics? It doesn't seem to make sense. Here's my textbook's explanation.
A particle has position vector \vec{r} in a non-rotating, inertial reference frame (the 'un-prime' frame). Suppose we want to observe the motion of this object in...
My textbook basically defines an inertial reference frame as follows: If you have an object O that has no forces acting on it, and there is a reference frame R where the acceleration of O with respect to R is zero, then R is a inertial reference frame.
This to me seems circular. How does one...
Hi - I've just started having lectures on special relativity at uni. We were talking about inertial reference frames and how these can be characterised by the facts that:
1) They move relative to one another with constant velocity, and
2) Newton's laws operate in inertial reference frames...
under which conditions we could say that the same experiment is performed in different inertial reference frames. I have formulated for myself the following answer:
We say that observers from two inertial reference frames perform the same experiment if the physical quantities they measure are...
Hi,
Please help me, I can't make head or tail of the concept of an inertial reference frame. What is an inertial reference frame? In what fundamental way does it differ from a noninertial reference frame if all motion is relative? Thanks for your help.
Molu
1) Which object provides an inertial frame of reference?
a. the tip of the moving second hand of a clock
b. a rock thrown vertically upward
c. a pendulum swinging with no air resistance
d. a skydiver falling at terminal velocity
At first I thought c might be correct, but now I am...
I can make a local inertial reference frame in a gravitational field by creating a frame that is small but close to the source of curvature of space-time.
Alternatively I can make a local inertial reference frame by creating a frame that is large but a long distance from the source of curvature...
Suppose 2 inertial frames with relative relativistic velocities.
To discuss phenomena in other frame, we need to use Lorentz Transform for length and time. I got question: do we have to also use LT to talk about permittivity and permeability of other IRF? This seems strange. Permittivity has...