# Questions tagged [inertial-frames]

A specific reference frame that describes its coordinates in a manner that does not depend on time and is isotropic.

1,142 questions
Filter by
Sorted by
Tagged with
195 views

### Definition of Newton's first law [duplicate]

I have always had a doubt in the definition of the Newton's first law. In general, it is stated in a form like: An object at rest remains at rest, or if in motion, remains in motion at a constant ...
55 views

### Necessity to consider the square of Four Momentum

Why do we often need to consider the square of four momentum transfer $Q$ in scattering experiment or particle physics/cosmology instead of just the $Q$ itself?
118 views

### In what sense do photons exist?

In a photon's frame of reference travel is instantaneous, so presumably a photon cannot exist in its own frame of reference. I am not aware that a "beam" of photons interacts via gravity despite ...
1k views

### Lorentz invariance of Maxwell's equations in matter

I know that Maxwell's equations of electromagnetism are Lorentz invariant in a vacuum. But what about in a generalized medium, e.g. a metal, a rubber, a dielectric, a magnet? I have read it comes down ...
151 views

### Newton's First Law and things that are very old [closed]

Recently I've been revisiting physics text books, and books by Feynman, and others. A curious thought has arisen, while I was reading about Mach's principle, and it seems to gnaw on my mind. I hope ...
233 views

### Twin paradox - is acceleration relative? [duplicate]

The usual answer to the twin paradox is that the twin who undergoes acceleration is the one who finds the other has aged more, because the trajectory of the 'travelling twin' does not amount to a ...
70 views

### Isn't inertia experience by person in moving bus same as torque

When a bus moves suddenly, the person standing in it tilts backwards. This concept is explained using inertia(tendency of body to resist change in its state of motion) but when the bus moves suddenly, ...
32 views

### Invariance of forces

In Newtonian mechanics, the inertial forces depend on the reference frame and the other forces are invariant. Are they still invariant when special or general relativistic effect are involved?
36 views

### What is proper name for non-inertial forces in GR?

General relativity works in all reference frames, so inertial forces are real in it. And due to the equivalence principle, gravity should be also considered inertial. So what is a good term for the ...
139 views

### Why does time slow down ONLY for objects travelling at high speeds?

Today in physics class, we learned about the theory of relativity and how it relates to time dilation. We were given the example of two photon clocks- one stationary relative to the Earth, and the ...
59 views

### Speed of light as the maximum speed and movement course

Assuming we have 3 objects d,e,f moving on the same line while e is stationary, d is moving to the left at 'almost speed of light' and f is moving to the right at 'almost speed of light'. What is the ...