What is Inertial: Definition and 496 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.

View More On Wikipedia.org
Recent contents Top users
  1. N

    Inertial Forces: Exploring Their Major Properties

    Hi everyone ! Which are the major properties of inertial forces ?
  2. N

    Inertial and Gravitational Mass

    Hi everyone! In an university examination it was asked to:"Explain the difference between inertial and gravitational mass" but my physics book is not very exhaustive on these differences. Which could it be a precise answer to this question ?
  3. S

    Understanding Inertial reference frames

    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...
  4. V

    Locally inertial coordinates on geodesics

    It's a standard fact of GR that at a given point in space-time, we can construct a coordinate system such that the metric tensor takes the form of Minkowski spacetime and its first derivatives vanish. Equivalently, we can make the Christoffel symbols vanish at point. Moreover, the fact that, in...
  5. G

    Relation between binding energy and inertial mass

    This question has been bugging me for a while now. I roughly understand how the Higgs mechanism gives elementary particles their rest mass and I also understand that gravity couples to all forms of energy, including binding energy in a nucleus or atom. I also know most of the mass of a system...
  6. Telemachus

    Generalized momentum and Hamiltonian over a non inertial reference frame

    Hi there. I need help to work this out. A particle with mass m is studied over a rotating reference frame, which rotates along the OZ axis with angular velocity \dot\phi=\omega, directed along OZ. It is possible to prove that the potential (due to inertial forces) can be written as: V=\omega...
  7. S

    Velocity in Inertial Frames: Lorentz Dilation and Contraction

    i was looking at the lorentz dilation and contractions for SR. My books says they are \grave{l}=l\gamma and that \grave{t}=\frac{t}{\gamma} .what i don't understand is that the velocity in the unprimed system is then \frac{l}{t} but in the primed system its \frac{l\gamma^{2}}{t} which is not...
  8. P

    Newton's law in non inertial frame.

    Please explain the concept of pseudo forces by considering an example of two cars say A and B, accelerating in the same direction. How will Newton's law applied to the man in car B as noted by the man in car A differs from that of the man standing on the earth? And how will the man in car A...
  9. S

    Basic question about inertial reference frame

    I have no background in relativity. Recently I started reading some introduction to special relativity in Griffith's EM book, where he vaguely defined an inertial reference frame as one in which Newton's first law holds. Now according to this definition, does such frame exist in nature? On...
  10. G

    Is the inertial mass of light relative?

    By the equivalence principle, the gravitational mass of light is its inertial mass, which it has because it has momentum. Light can impart some of its the momentum to massive objects, upon which it will lose energy, which is manifested by its frequency (the basic principle behind doppler...
  11. B

    Need help understanding inertial frames of reference

    Need help understanding inertial frames of reference! I'm doing an A2 physics unit on special relativity (AQA) and am really confused about this, but I only want to get the idea so don't go to deep please :) I understand that a frame of reference is an area which is fixed relative to...
  12. L

    Non inertial or inertial reference frame?

    Homework Statement Specify and explain whether the following is an inertial or non-inertial observer: An observer is placed on a rock between Andromeda and the Milky Way. Homework Equations N/a The Attempt at a Solution So here is my understanding, the observer would be situated...
  13. J

    Can we extend our inertial frame globally?

    People tell me that we cannot extend our inertial frame, as defined in special relativity, across the Universe because that would be in violation of general relativity. The problem is that general relativity says that space-time can be curved whereas a global inertial frame assumes flat...
  14. A

    How inertial frame of reference differs from non-inertial frame?

    We know that we can't say whether we are at rest or uniformly moving if we're in a einstein cage..but if the same medium is accelerating/decelerating can we being inside(and can't see outside) claim abt state of cage..?I ve read that a non-inertial can be converted to inertial by incorporating a...
  15. R

    Velocities in inertial and rotating frames of reference

    Hi, I have a couple of questions about velocities in inertial and rotating frames of reference, related by the following equation: \mathbf{v_i} \ \stackrel{\mathrm{def}}{=}\ \frac{d\mathbf{r}}{dt} = \left( \frac{d\mathbf{r}}{dt} \right)_{\mathrm{r}} + \boldsymbol\Omega \times...
  16. J

    Inertial adn non-inertial frames

    i know these topics are discussed many times and i have read many of them but still have a doubt. Suppose a car is accelerating and there is an object and a man in the car. Object is ofcourse at rest with respect to man. The man does not know if the car is accelerating or not - he just sees...
  17. D

    A problem on angles from different inertial frames

    Homework Statement A rod lies at an angle α with the x'-axis of an inertial frame moving at a speed v along the x-axis(x and x' are parallel) of another inertial frame. The rod makes angle β with the x-axis of this frame. Find the relation between α and β. Variables: α,β,v and define...
  18. W

    4-vector law of motion in different inertial frames

    Newton's second law of motion is given in Minkowski space by \bar{F}=m(c\gamma\dot{\gamma}, \gamma\dot{\gamma}\tilde{v}+\gamma^{2}\tilde{a}) where \dot{\gamma}=\frac{d\gamma}{dt}=\frac{\gamma^{3}}{c^{2}}\tilde{v}\cdot\tilde{a} and \tilde{v}(t) and \tilde{a}(t) the 3-velocity and...
  19. B

    Magnetic force in a moving inertial reference frame

    A charged particle is placed next to a current-carrying wire. The wire produces a magnetic field, but if the particle is at rest, the field exerts no force on it. However, in a different inertial reference frame moving at speed v parallel to the wire, the particle is seen to be in motion, and so...
  20. M

    Torque in a non inertial reference frame

    Hi, This is partly inspired by the questions in the thread about normal forces on a cornering car but I thought I'd post here instead of mix that thread up with my question. So suppose we have a biker leaning into a corner. There are the normal force and the force of friction which act at the...
  21. M

    Why do Newton's laws only apply in inertial reference frames?

    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...
  22. R

    Calculating Time Interval and Speed of Inertial Clock

    Homework Statement In the Home Frame, two events are observed to occur with a spatial separation of 12ns and a time coordination separation of 24ns. A)An inertial clock travels between these events in such a manner as to be present at both events. What timer interval does this clock read...
  23. M

    Problems with Inertial Reference Frames

    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...
  24. N

    Origin in Inertial Frame for Spin-Orbit Coupling?

    Hello, I've seen spin orbit coupling being explained by going to the rest frame of the electron and noting that the proton is then a moving charge and hence has a magnetic field, which interacts with the spin of the electron, effectively coupling the spin and angular momentum of the electron...
  25. S

    Inertial frames and related predictions

    As a result of observations made over many, many years, physicists have inferred that: "No experimental test provides any way to distinguish an inertial frame from another." This negative form of the statement is important, as it is a prediction which can be tested experimentally and thus...
  26. M

    Isotropy/Homogeneity of Spacetime and Inertial Frame Equivalence

    So this is problem 11.1 out of Jackson Electrodynamics: Two equivalent intertial frames K and K' are such that K' moves in the positive x direction with speed v as seen from K. The spatial coordinate axes in K' are parallel to those in K and the two origins are coincident at times t=t'=0. (a)...
  27. V

    Does time period of SHM vary with frame(inertial and non inertial)?

    Does time period of SHM vary with frame(inertial and non inertial)?? Homework Statement There is an SHM. First observer is watching it from inertial frame of refrence and secodn is from non inertial will there any change of time period for both observer. Homework Equations just think...
  28. V

    Do our inertial frames rotate with the Milky Way?

    In a 1925 paper, Erwin Schrödinger mentions that "our inertial systems are free of rotation precisely with respect to our stellar system", instead of being "anchored...in much more distant stellar masses". Is this really the case? If so, this suggests that the total gravitational potential...
  29. P

    How to Implement Inertial Navigation System Equations in MATLAB?

    Dear :), could some one please guide me in the right direction to answer the following questions: 1) using MATLAB, implement the differential equations that describe the evolution with time of along-track , cross-track and vertical position. (Inertial Navigation System). and 2) for a...
  30. J

    How can Higgs field explain proton's inertial resistance to acceleration?

    If most of the mass/energy of a proton is due to the kinetic energy of its quarks and gluons, rather than interaction with the Higgs field, then how can we explain its inertial mass, i.e. its resistance to acceleration, as being due to a drag induced by the Higgs field? Alternatively imagine...
  31. F

    Do the electrons have inertial mass?

    Hello there! According to quantum physics, do the electrons have inertial mass? I read somewhere electrons were an amount of energy, with no mass at all. I think I'm confused about the concept of "mass" since I know two, the one they taught me at school, which I'm considering as inertial mass...
  32. C

    Discussion of Inertial Frames of Reference

    Post any thoughts or ideas here.
  33. C

    Why extremal aging, not just maximal? (for an inertial body in spacetime)

    One can use the Principle of Extremal Aging to calculate the path of a freely moving body (in an inertial frame not subject to any forces) in spacetime, curved or flat. Why extremal? Why not just maximal? All the examples I know of involve maximum proper time for a freely moving body. For...
  34. G

    SR, Inertial frames, Movement, Testing

    I wanted to understand something about Inertial frames especially as they are talked about in SR. It appears that the laws of physics should hold the same in them. Now I understand that inertial frames only involve things moving relative to each other and moving in constant speed so you can...
  35. G

    Can any one explain Schuler cycle in Inertial Navigation System

    Can anyone please explain schuler cycle, please don not start explaining with same old pendulum with the length of radius of Earth stuff. why is it required ? what is that all about ?
  36. Z

    Difference between the inertial and gravitational mass

    I'm trying to learn what is the difference between the inertial and gravitational mass. According to: http://www.physlink.com/education/askexperts/ae305.cfm and https://www.physicsforums.com/showthread.php?t=147282 there is practically no difference (as stated by the Equivalence principle)...
  37. K

    Why is inertial mass not an observable in QM?

    In classical mechanics, I can measure the inertial mass of a particle by measuring force and acceleration: m=F/a. In QM, this equation only holds for expectation values <F> and <a>. Does this lead to the fact that inertial mass is not an observable? Is there a deeper underlying principle which...
  38. T

    Inertial reference frames and Newton's Laws of Motion

    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...
  39. P

    Why so many definitions of an inertial frame?

    A Newtonian inertial frame is one where objects obey Newton's first law. Schutz (A first course in general relativity) says an inertial frame cannot be constructed in a gravitational field because it's then impossible to synchronize the frame's clocks? For the same reason an inertial frame...
  40. J

    Are You an Inertial Observer on a Constantly Moving Turntable?

    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...
  41. E

    Inertial frame of reference of light speed (And beyond)

    Hi All! I found discussions on this here while researching the subject to see if anyone else has attempted to explore the subject. I saw that several people asked questions pertaining to this, but the question was never really answered. It seemed unanswerable. While many discussions of...
  42. S

    Pendulum on Pendulum, velocity in non inertial frame

    Homework Statement A double pendulum consists of two particles of equal mass m suspended by massless rods of equal length l. Assuming that all motion is in a vertical plane: 1. Find the Lagrangian of this system. 2. then find the equations of motion and, 3. linearize these equations...
  43. P

    Train inertial referance frame

    Homework Statement You are in a train traveling on a horizontal track and notice that a iece of luggage starts to slide toward the front of the train. from this observation you can conclude that this train is not an inertial reference frame because it is slowing down. Homework Equations...
  44. S

    Acceleration measured in another inertial frame?

    Suppose, in the first case, that an object (initially at rest in frame S) accelerates, for whatever reason upward, with a force F. Let M be the relativistic mass of the object. The force measured in frame S is relativistically given by: F_s=γ^2...
  45. S

    Test your knowledge of inertial forces

    We have had several threads lately discussing the nature of inertia and inertial forces. Here is a practical exanmple for open discussion. Take a flexible bar and closely thread several masses onto it. Clamp both ends. Arrange a disturbance to provide a flexing of the bar. This will...
  46. E

    Definition of local inertial frame

    I have a question I wanted to clear up. According to the definition of a "local inertial" frame in GR, you must use a coordinate system that locally looks Cartesian, right? I mean if you had a coordinate system with a basis that wasn't orthogonal, then it would not be considered a local inertial...
  47. T

    Lorenz transformations for two parallel inertial systems

    Thanks for reading! Homework Statement I have been given a proof for the lorentz transformations (which I only partly understand) that relied on the two relativity postulates (equivalence of inertial systems and the speed of light being constant) for the case of two standard inertial...
  48. R

    Navier Stokes Equation Derivation and Inertial Forces

    Hi I was reading Introduction to Fluid Mechanics by Nakayama and Boucher and I got lost in their derivation of the Navier Stokes Theorem. They basically started out with a differential of fluid with dimensions dx, dy, and b. Then they say that the force acting on it F = (F_x, F_y) is F_x...
  49. M

    Studying Relativity: Speed Limit of c in All Inertial Frames?

    How I studied relativity, we postulated that a particle traveling at c in one inertial frame travels at c in all inertial frame. But now looking through a book, I see that they just postulate that all laws of physics are same in all inertial frames, and that there is a speed limit (c). However...
  50. B

    A basic doubt (about inertial frames)

    Hi This question is taken from the book Classical mechanics by Gregory. Please clear this doubt TIA ------------- Suppose that a reference frame fixed to the Earth is exactly inertial. Which of the following are then inertial frames ? A frame fixed to a motor car which is (i) moving...
Back
Top