What is Non inertial frame: Definition and 16 Discussions

A non-inertial reference frame is a frame of reference that undergoes acceleration with respect to an inertial frame. An accelerometer at rest in a non-inertial frame will, in general, detect a non-zero acceleration. While the laws of motion are the same in all inertial frames, in non-inertial frames, they vary from frame to frame depending on the acceleration.In classical mechanics it is often possible to explain the motion of bodies in non-inertial reference frames by introducing additional fictitious forces (also called inertial forces, pseudo-forces and d'Alembert forces) to Newton's second law. Common examples of this include the Coriolis force and the centrifugal force. In general, the expression for any fictitious force can be derived from the acceleration of the non-inertial frame. As stated by Goodman and Warner, "One might say that F = ma holds in any coordinate system provided the term 'force' is redefined to include the so-called 'reversed effective forces' or 'inertia forces'."In the theory of general relativity, the curvature of spacetime causes frames to be locally inertial, but globally non-inertial. Due to the non-Euclidean geometry of curved space-time, there are no global inertial reference frames in general relativity. More specifically, the fictitious force which appears in general relativity is the force of gravity.

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  1. Spector989

    Conservation of momentum and mechanical energy on an inclined plane

    So i am tried to conserve momentum and use conservation of mechanical energy but won't there be psuedo force acting on the block if i am solving from non inertial frame ?. If i ignore the pseudo force and simply use C.O.M.E and include the K.E of the wedge and solve normally i do get the...
  2. LCSphysicist

    Lagrangean and non inertial frame

    I have tried to solve this problem using the lagrangean approach: $$L = T - V = m((\dot r)^2 + (r \dot \theta)^2)/2 - 0 = m((\dot r)^2 + (r \delta)^2)/2 - 0 $$ The problem is that the answer i got is the right answer at the smooth rod referencial, that is, at the non inertial frame. Now we can...
  3. Like Tony Stark

    Write the equations of a mass and spring in different accelerated systems

    Hi I know that the equation of a simple harmonic oscillator is ##\ddot x + \omega^2 x=0##. The thing is that I don't know how to get to that equation in the situations given. In the first situation, I know that ##x) k(x-x_0)=m(\ddot x -x \dot \theta ^2)## ##y) N=m(2 \dot x \dot \theta)## So...
  4. LCSphysicist

    Trajectory in a non inertial frame

    Well, make the center of the polar coordinates at the center of the turntable, so put r along the ro initial. I am well known that to someone who is rest on the turntable, the equations will be the follow: dr/dt = ro - vt If the turntable route with angular velocity w, dtheta/dt = -wt We...
  5. cianfa72

    I Speed of Light in Vacuum in Non-Inertial Frame

    Hi, I read various threads in PF about the concept of invariant speed and the speed of light in vacuum that in our universe happens to be the same as the 'invariant speed'. My doubt is about the speed of the light in vacuum as measured from a non-inertial frame (basically in the context of SR...
  6. JD_PM

    Man walking on a rotating merry-go-round

    Some information Newton's second law in a non-inertial frame is given by: Where: 1) ##A## is the translational acceleration, ##\Omega## the angular velocity and ##\dot \Omega## the angular acceleration (all relative to the inertial frame attached to the ground ##F##). 2) r', v' and a' are...
  7. parshyaa

    Question related to inertia and non inertial frame

    Suppose a person is standing in a bus, moving with constant velocity and then driver applied the breaks and the person standing moved forward as if something pushed him from behind Whats the reason behind this Is it because bus has become a non inertial frame and we have to add psuedo forces to...
  8. parshyaa

    Question based on non inertial frame of reference

    Suppose I am observing a object in a noninertial frame from a noninertial frame , then what will happen to the forces acting on a object with respect to both the frames, frame of reference (FOR) moving uniform with inertial FOR are themselves inertial frame , does it follow the same with a FOR...
  9. T

    Non inertial frame of reference(rotating)

    Homework Statement $$g_o=\frac{GM}{R^2}e_R$$ where g0 is the gravitational acceleration, G = 6.67 * 10-11Nm2 /kg2 is the universal gravitational constant, M= 5.98 *1024 kg is the mass of the Earth, and R = 6.38 * 106 m its radius $$g = g_0-ω*[ω*(r+R)]$$....(8.29) where gravitational...
  10. O

    Inertial and non inertial frame of reference

    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...
  11. L

    Pendulum in non inertial frame

    Homework Statement A pendulum is placed on a rotating platform which rotates with angular velocity ω around an axis, at equilibrium the angle between vertical and pendulum is θ θ= 20 degrees ω= 10 1/s how far is the pendulum placed from the axis Homework Equations...
  12. 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...
  13. 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...
  14. L

    Non inertial frame: Speed of light

    The speed of light is not constant in a non-inertial frame; the light accelerates with the acceleration of the observer in reverse direction. Consider the following problem: If a light pulse is created in an inertial frame at some time, t<0 (say t=-10); the light pulse moves at velocity c...
  15. P

    Light speed in a non Inertial frame of reference

    Does the principle of invariant light speed still hold in a non Inertial frame of reference? Thank you!
  16. R

    Newton's laws and non inertial frame of reference

    Hi all Why do we actually say that Newton's laws do not hold for non inertial frames. can you folks give me an example of how Newton's laws collapse in an non inertial frame(if they do at all)