What is Non-inertial frame: Definition and 53 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.
Q： Referring to the solution of this problem, why does the equation (eq) hold true?
$$
\frac{\partial}{\partial t}\int_{CV}^{}{u_{xyz}}\rho d\forall =\frac{\partial}{\partial t}\left( u_{xyz}\cdot M \right) =M\left( \frac{\partial}{\partial t}u_{xyz} \right) =M\left( \frac{\partial}{\partial...
Q： Regarding item (4), my understanding aligns with (eq_1), where M is a constant. However, why does ##\left( \frac{\partial}{\partial t}u_{xyz} \right)## in (eq_1) equal 0?
$$
\frac{\partial}{\partial t}\int_{CV}^{}{u_{xyz}}\rho d\forall =\frac{\partial}{\partial t}\left( u_{xyz}\cdot M...
It's known that in inertial frame, space is isotropic. (statement of this where I have taken out of is attached as image)
When we talk about an uniform accelerated train, ground frame is considered as inertial frame(at least in newtonian mechanics). So if ground frame is considered such as...
Hello, everyone!
In the first few chapters of Physics 1, there is the description of motion, and the computation of the acceleration vector as being the sum of the rate of change of velocity, with the division of linear velocity squared by the instant radius of curvature:
The above equation...
It's frequently discussed Galilean transformation brings one inertial frame to another inertial frame, and such a transformation leaves Newton's second law invariant (of the same form). I wonder what happens for non-inertial frame? If we start with a non-inertial frame, and Galilean transform...
In learning about translational and rotational motion, I solved a problem involving a wheel rolling down an inclined plane without slipping.
There are multiple ways to solve this problem, but I want to focus on solutions using energy.
Now to my questions. The reference frame in the posted...
Does the position of the origin for the body’s rotating coordinate frame
1) stay fixed to the moving body or
2) does it stay fixed to the inertial frame, yet still able to rotate as the body rotates with the only restriction that it cannot translate with the body i.e. only affixed at the...
If a frame is a non inertial frame, then it must have an acceleration. Then which reference frame is this acceleration with respect to? If this acceleration varies with the reference frame this acceleration is calculated with respect to, is this non inertial frame absolute?
Hi,
I was wondering, if the charges do not move in a non inertial frame and I don't move too in this frame, will I see the same Coulomb force, some fictitious forces and radiation coming from these static charges?
Thanks!
In the frame of the accelerated block, I applied the non-inertial force F'. My doubt is if I can conserve the mechanical energy in the accelerated frame and find the speed at the top. Otherwise, how could you proceed.
(a) No, a person seated inside the train compartment will not be able to tell whether the train is accelerating on a horizontal track or moving uniformly up an inclined track by observing the plumb line.
(b) I am assuming that both observers are not allowed to look "out" of the boundaries of...
Question: If we place the frame of reference on an accelerating point, does the total rotational momentum still remain the same?
I attempted to solve this question by manipulating the equations as shown below.
$$\text{Define that }\vec r_i=\vec R+\vec r_i'\text{, where r is the position vector...
Let's suppose there's some platform that is rotating with angular speed omega and has a radius R. At t=0 we release some object from the border, which has an initial speed perpendicular to the radius direction with magnitude \omega R and we want to know its position at t=T with respect to the...
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...
I have some difficulties trying to understand non-inertial frames.
I have problems to notice the acceleration in these cases, from an inertial reference frame and from non inertial refrence frame.
Consider the first case, if I'm on the wedge, I see that the block doesn't move so there's no...
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?
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 am reading through a textbook on AP Physics, and I came across a few references to non-inertial frames of reference. It doesn't clearly say what a non-inertial frame of reference is. Based on the examples it gives, I assume that it is a frame of reference where the observer is experiencing...
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...
Homework Statement
Take the x-axis to be pointing perpendicularly upwards.
Mass ##m_1## slides freely along the x-axis. Mass ##m_2## slides freely along the y-axis. The masses are connected by a spring, with spring constant ##k## and relaxed length ##l_0##. The whole system rotates with...
In this example I'd like to know about the output of the transformer. What happens if an electromagnetic transformer is powered by a sine-wave and simultaneously accelerating at non-relativistic speeds?
I assume the output will still be a sine-wave but the frequency will change. Is this correct?
Hi,
in this Landau's extract i note that the total derivative is neglected in 2 places.
in the first case i think because it's raised twice, but in the second case?
Hello,
I was referring to this thread: https://www.physicsforums.com/threads/accelerating-atwoods-machine-problem.44305/ to solve a problem on accelerating atwood machines in which, naturally, one attempts to find the acceleration of each of the individual masses.
Although I now understand how...
Homework Statement
Because of the Coriolis force, falling objects on the Earth are deflected
horizontally. For instance, a mass dropped from a tower lands to the
east of a plumb line from the release point. In this example we shall
calculate the deflection of a mass m dropped from a tower of...
Homework Statement
A bead slides without friction on a horizontal rigid wire rotating at
constant angular speed ω. The problem is to find the force exerted on
the bead by the wire. Neglect gravity.
Homework EquationsThe Attempt at a Solution
The physical force acting on the bead is the force...
As far as I understand it, the Lorentz factor ##\gamma(\mathbf{v})## is constant when one transforms between two inertial reference frames, since the relative velocity ##\mathbf{v}## between them is constant.
However, I'm slightly confused when one considers four acceleration. What is the...
Hello all, new member here. Signed up cause I am stumped by a physics problem.
I am trying to size a linear actuator. Basically I have a large body that is accelerating at acceleration in x direction. I have a linear actuator aligned in the x direction that is rigidly attached to the large body...
How (more accurately) Earth is a non inertial frame?
A frame of reference(FOR) will be a non-inertial when a=0 ⇔ F =0
Suppose a book on a table is our object and Earth as a Frame of reference, generally we take accelaration of book w.r.t Earth as 0 but more accurately it is not 0(because...
This (photo) is a very typical example of conservation of angular momentum, but my trouble arrises from trying to prove that the difference of energy will have to correspond to work, by calculating the work done by you to alter the moment of inertia. I have spent a lot of time in this, but I...
Homework Statement
Consider the pendulum depicted in the adjacent figure: a mass m
is attached to non stretching chord of length `. Directly below the
pendulum is a circular disc rotating with constant angular velocity
w. We attach to the disk a frame whose x-axis is in the plane of the...
I'm trying to understand the relativistically spinning disk within the framework of SR (if that is even possible). I thought to first simplify the problem by considering a spinning ring/annulus, but I don't know if my analysis is correct.
I imagined a spinning ring of radius R, spinning at an...
I'm trying to get my head around GR. As I understand it, any frame of reference is as valid as any other for modeling the universe. Therefore, it is valid to use a non-rotating Earth as a frame of reference, and try to model the movement that is seen from this frame.
But if that is true, I...
I have been asked by someone if it is true that in general, for a constantly accelerating reference frame, i.e. a non-inertial reference frame, the acceleration of a particle (as observed in this frame) due to the corresponding fictitious force is independent of its mass.
My response was yes...
Homework Statement
Why do objects that have no external net force acting on them accelerate? Ex. If a ball is on an accelerating train, it will accelerate opposite the direction of the train's acceleration, assuming there is nothing blocking its path of motion and it is not strapped down. My...
Homework Statement
You are in a car accelerating forwards. There is a baseball at your feet. Draw two FBDs showing the the ball's motion from the frame of reference of the car and the frame of reference of the sidewalk. Which frame of reference is non-inertial? In which frame do you observe the...
Homework Statement
You use a string to suspend a cork ball with a mass of 22.0g from the ceiling of a moving speedboat. The ball and string hang at 32.5 degrees from the vertical. Calculate the acceleration of the speedboat.Homework EquationsThe Attempt at a Solution
I was able to calculate...
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...
I confuse when should I use non-inertial frame...
is there any keyword or key clues that remind you of using non-inertial frame of reference?
can anyone help explain this with an example?
I was just thinking about this, and from a perspective of an inertial frame, it's easy to see how distances contract, times dilate, simultaneity varies between observer and the speed of light is exactly c in each case.
But what about non-inertial frames? In the presence of gravity almost...
Homework Statement
In opposite points carousel diameter D = 20 m, rotating with constant angular acceleration, located at the point C shooter and target M. Shooter aiming at a target without introducing amendments to the rotation of the carousel. What should be the angular acceleration of...
In class, we came up with an equation, a=gtanθ, to calculate the acceleration of a car using a hanging pendulum in Earth's frame of reference (θ being the angle that the pendulum makes with the vertical when the car accelerates). So far, I know that that the pendulum moves in the opposite...
Homework Statement
Consider a bead of mass m on a loop of radius R. The loop is rotating at a constant rate ω. Using a non-inertial frames of reference, find all equilibrium points of the bead on the loop.
Homework Equations
\vec{F_e}=m\vec{a_r}...
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...
Homework Statement
Consider the bead threaded on a cicular hoop of example 7.6 (pg 260), working in a frame that rotates with the hoop. find the equation of motion of the bead, and check that your result agrees with eq 7. 69. Using a free body diagram explain the result 7.71 for...
Are there lorentzian transformation equations relating non-inertial frame to inertial frame. Also are there transformations relating non-inertial frame to another non-inertial frame. By 'non-inertial frame', I mean frame of reference having absolute acceleration,jerk... or any n-th order time...
Okay, so I know what inertial and non-inertial frames of reference are:
1. Inertial is when Newton's laws of motion hold.
2. Noninertial is when they do not hold (the object is accelerating without a force).
And I have a few examples as well, such as when you are is in a car and the car is...
Major difference of Inertial and non-inertial frame of reference ??
What is the major difference or differences of Inertial and non-Inertial frame of reference??
Is it only:
Inertial - Constant velocity, obeys the law of inertia
Non-inertial - Acceleration, disobeys the law of inertia
Considerer a closed box into space:
• In constant acceleration.
• Turning around its axis.
Einstein used the first case as a thought experiment (http://galileo.phys.virginia.edu/classes/252/mass_and_energy.html) that led to the general theory of relativity: the occupant of the box could...
I am doing some study about the lorentz transformation between non-inertial frames. I wonder if the tranformation is the same as in SR. I need to do the transformation of EM fields in a constantly rotational frame. Can anybody help me with this one. Is there anybook I can refer to? Many thanks.