The reference-frame tag has no wiki summary.
0
votes
0answers
22 views
Short term track of a hand held sensor (gyro, accelerometer) data with rough precision
I have acceleration and attitude data for the movement of a device in 3d space. what transformations, before numerical integration, are required, in order to produce a 3D track of the the movement in ...
6
votes
2answers
117 views
Confusion with derivation of fictitious forces
I read the mathematical derivation of fictitious forces on Wikipedia and I'm having trouble understanding it. I went on a few other sites looking for a better derivation, but they're all basically the ...
4
votes
4answers
125 views
When we talk about speeds in relativity theory, where are they measured?
I recently asked a question here about if the direction we travel matters in relativity theory:
Does it matter in which direction I travel in relativity theory?
After I got answers and making more ...
0
votes
1answer
66 views
Vectors on Different Coordinate Systems? [closed]
Consider the product of vectors coordinated relative to a given coordinate frame, defined by
$$\vec{a}\square\vec{b}=((a_{1},b_{1})\square(a_{2},b_{2})):=(a_{1}b_{1},a_{2}b_{2})$$
Explain why ...
2
votes
2answers
33 views
Velocity in a turning reference frame
I often see the relation that $\vec v=\vec v_0+ \vec \omega \times \vec r$ in a turning reference frame, but where does it actually come from and how do I arrive at the acceleration being $$\vec ...
2
votes
0answers
36 views
Is it possible to have uniform proper acceleration along a large object without breaking it?
I'm learning about accelerating reference frames (to eventually get grasp of general relativity too).
I've just read about the Rindler coordinates and this one caught my eye
Note that Rindler ...
0
votes
2answers
75 views
Relative to the speed of light
Einstein's relativity tells us that light always travels at the speed of light relative to me, no matter how fast I'm going. Right? This really confuses me though. If light travels from A to B in one ...
0
votes
1answer
54 views
How can we observe lights properties if it travels at the speed of light, or can we? [duplicate]
Special relativity says that anything moving (almost) at the speed of light will look like its internal clock has (almost) stopped from the perspective of a stationary observer. How do we see light as ...
2
votes
1answer
61 views
Quantum Mechanical Effects of an object accelerating near speed of light $c$?
Consider a space ship, undergoing constant acceleration (which for our purposes means that the same amount of energy is being used per second to increase its speed). According to special relativity ...
6
votes
2answers
164 views
How fast can time flow? A question of time dilation
(I would describe myself as an illiterate physics enthusiast, so I hope you'll forgive me if my ignorance is borderline offensive.)
If I've understood anything of the concept of time dilation, your ...
2
votes
1answer
83 views
If time stops at the speed of light is a photon 'everywhere' at once? [duplicate]
I am not a physicist so excuse my question if it's paticularly stupid. As a particle gets closer to the speed of light time slows down as for that particle as compared to a reference from the ...
3
votes
0answers
125 views
Tensor equations in General Relativity
In the context of general relativity it is often stated that one of the main purposes of tensors is that of making equations frame-independent.
Question: why is this true?
I'm looking for a ...
0
votes
1answer
63 views
Difference between velocity vectors, relative speed
Consider two particles moving in the same direction instantaneously but one of them follows a circular path and one follows a straight path.
If I adopt a rotating frame of reference in which the ...
1
vote
1answer
43 views
Problem with a rotating frame of reference on the South pole
Consider this problem:
A high-speed train is traveling at a constant 150 m/s (about 300 mph)
on a straight horizontal track across the south pole. Find the angle
between a plumb line suspended ...
2
votes
2answers
103 views
Does inertia increase with speed?
I have heard that when the speed of the object increase, the mass of the object also increase. (Why does an object with higher speed gain more (relativistic) mass?)
So inertia which is related to ...
0
votes
2answers
39 views
Viewing a reference frame from inside of it?
Can one observe one's own frame of reference without moving out side the frame?
For example, if you are on a train and you throw ball in the air up and down.
When you are on the train (frame 1) you ...
1
vote
1answer
104 views
The definition of Lorentz transformation
I know that the Lorentz transformation, when two frames $\mathcal{S}$ and $\mathcal{S}'$ are in standard configuration (the axes are all parallel to their counterparts in the other inertial frame) is ...
0
votes
2answers
54 views
Simple conservation of momentum and frame of reference problem
I'm making a very simple physics engine based on momentum, and I'm solving what response to use for a collision from each involved object's frame of reference. However, something about how I'm ...
4
votes
2answers
178 views
What is the Andromeda Paradox?
I have been studying causality (specifically why there is no such thing as a simultaneous instant of time across all observers) recently and I keep hearing references to the Andromeda paradox. Can ...
0
votes
3answers
118 views
Stuff can't go at the speed of light - in relation to what? [duplicate]
We all know that stuff can't go faster than the speed of light - it's length becomes negative and all kinds of weird stuff happens.
However, this is in relation to what? If two objects, each moving ...
1
vote
4answers
184 views
What is the exact mechanism by which time dilates?
What is the exact mechanism by which time dilates for a fast moving object?
Can the time dilation be explained by any theory other than relativity?
1
vote
1answer
69 views
Local inertial coordinates
It is said that we can introduce local inertial coordinates for any timelike geodesic. But why only for timelike geodesics? What about null geodesics? Perhaps it has to do with invertibility or ...
0
votes
3answers
125 views
How to create frame of reference?
Is this possible to create a inertial frame of reference in the earth?
How it is possible?
2
votes
1answer
142 views
Space time a function of itself, objects in it, or both?
Is spacetime a function of itself, objects within it, or both? I am struggling to understand just what is spacetime without objects in it (or theoretical reference points) and thus no frame of ...
4
votes
1answer
63 views
Relativity of simultaneity - An example
I am trying to understand the relativity of simultaneity in different frames, and I am trying to work out an example.
Suppose along the x-axis there are two points 2000m apart. Event A happens at t=0 ...
1
vote
2answers
80 views
Gravity mitigated by velocity regardless of mass?
We know that a small object moving fast enough can pass by a planet and escape its gravity. Would this be (theoretically) true in reverse? Meaning a planet moving fast enough past a stationary smaller ...
1
vote
3answers
103 views
Special Relativity - speed of light question
Just a basic question:
I know that if you are traveling at $x$ speed the time will pass for you slower than to an observer that is relatively stopped. That's all just because a photon released at the ...
2
votes
1answer
87 views
Difference between proper and comoving frames
I'm reading this book "Introduction to Quantum Fields in Classical Backgrounds" by Mukhanov & Winitzki, and there in the chapter 8 "The Unruh Effect" they introduce 3 reference frames.
Laboratory ...
0
votes
0answers
104 views
About the theory of relativity
Why is speed of light constant in every non inertial frame of reference? Is there any theoretical explanation behind this postulate Since we cannot completely depend upon the experimental results?
1
vote
2answers
90 views
“as measured in a local Lorentz frame”?
I've seen the phrase "as measured in a local Lorentz frame" tagged on the end of so many sentences.
What does it mean precisely?
To give an explanation with an example, consider the context of ...
1
vote
1answer
49 views
kinetic energy of the stone
Suppose we have a man traveling in an open car (roof open) with speed $v$ towards right (man faces right). He throws a stone (mass $m$) towards right, in his frame-forward with speed $V$.
In the ...
2
votes
1answer
98 views
Lorentz invariance of the wave equation
I want to show that the 2-d wave equation is invariant under a boost, so, the starting point is the wave equation
$$\frac{\partial^2\phi}{\partial x^2}=\frac{1}{c^2}\frac{\partial^2\phi}{\partial ...
0
votes
0answers
57 views
Determining Ether Drag - Aberration of Starlight
In order to determine the relative motion between the Earth and the ether (the medium through which light supposedly propagated. It has zero density and complete transparency), scientists used the ...
0
votes
6answers
200 views
Inertial Frames of Reference - Inertial vs. Accelerated Frames
According to Robert Resnick's book "Introduction to Special Relativity", a line states the following as the definition of an inertial frame of reference: "We define an inertial system as a frame of ...
0
votes
2answers
111 views
Inertial Frames of Reference - Description of an Inertial Frame of Reference
An inertial frame of reference is described as being a frame of reference in which the first law of Newton (the law of inertia) holds. This means that all events as described with respect to this ...
2
votes
1answer
86 views
Explanation of a Foucault pendulum
The equations of motion of a Foucault pendulum is given by:
$$\ddot{x} = 2\omega \sin\lambda \dot{y} - \frac{g}{L}x$$
$$\ddot{y} = -2\omega \sin\lambda \dot{x} - \frac{g}{L}y$$
where $\omega$ is ...
0
votes
3answers
278 views
A man running on the treadmill
Imagine a man is running on a treadmill. His inertia with respect to floor will be zero because he is not moving with respect to floor. If both he and the tread mill suddenly stops he will not fall, ...
-3
votes
1answer
69 views
How would time duration and space distance change when we move in the speed of light? [closed]
It is possible to figure out how time duration and space distance change when we are close to the speed of light - but I am not sure what happens to them if we travel in the speed of light.
0
votes
2answers
97 views
Internal/Rotational angular momentum
I have some difficulties to understand the relation between the internal and the rotational angular momentum of a rigid body which is also known as König's theorem, so what physical intuition lies ...
2
votes
3answers
187 views
If time slows down when you move faster, does this give you an “effective speed” different from your proper speed?
Suppose you're travelling at 0.9c toward the sun, and you tag past the Earth and start a clock. Would Lorentz contraction/time dilation cause you to get to the sun faster than (about) 9 minutes ...
2
votes
0answers
76 views
Car parking special-relavity puzzle
Hi I read the following puzzle from an old text book long time ago. However it doesn't provide the answer. So what is the solution?
Let's suppose a car is going to park to a garage and the garage is ...
4
votes
2answers
281 views
Which is the axis of rotation?
This should be simple, but it keeps bothering me. If a rigid body has no fixed axis, and a torque (defined relative to a point $A$) is applied, it will rotate around $A$. But often I can also ...
13
votes
0answers
226 views
Anomalous target space diffeomorphisms for one-loop world-line integrals
The Schwinger effect can be calculated in the world-line formalism by coupling the particle to the target space potential $A$.
My question relates to how this calculation might extend to computing ...
0
votes
1answer
111 views
What is the maximum time dilation between two objects, if one is standing still and the other is moving at $c$?
What is the maximum ratio in the rate of change in time in reference to object $A$ which is standing still and object $B$ which is moving at the speed of light?
0
votes
4answers
233 views
The bigger the mass, the more time slows down. Why is this?
If I were to stand by a pyramid, which weighs about 20 million tons, I would slow down by a trillion million million million of second. Don't know if that's exactly right, but you get the point. Also, ...
0
votes
1answer
78 views
Speed of light in a given direction based on frame of reference [duplicate]
Possible Duplicate:
How is the speed of light constant in all directions for all observers?
Is the speed of light constant regardless of frame of reference? If not, why is it still measured ...
1
vote
1answer
185 views
Does the increase of (relativistic) mass, while flying near speed of light, has any impact on astronauts? [duplicate]
Possible Duplicate:
Would travelling at relativistic speeds have any impact on human biology?
I am asking myself this question for a few day. What is the answer on: Does the increase of ...
5
votes
3answers
422 views
Kinetic energy with respect to different reference frames
I'm having problems understanding the following situation. Suppose two 1-tonne cars are going with the same orientations but opposite senses, each 50 km/h with respect to the road. Then the total ...
0
votes
1answer
135 views
Does photon possesses no time to cover any arbitrary distance?
Photon travel 8 minutes (with speed $c$) from the sun to reach the earth. Any particle (or space-ship) with velocity $0.99 c$ covers the same distance (93 millions km) within less than 2 minutes ...
0
votes
1answer
111 views
Scattering Amplitudes in Centre of Mass Frame
I'm reviewing page 59 of the QFT notes here and am a little confused by a reference frame argument. You can compute the second order probability amplitude term for nucleon-nucleon scattering to be
...
