# Tag Info

1

The relative velocity between two points depends on the frame. In general, $A$ will see $B$ going at a different velocity than $B$ sees $A$. Imagine that, in your example, $\mathbf{V_B}=\mathbf{V_A}$ (zero relative velocity) in the inertial frame. In the rotating frame, $B$ will lag a bit behind, because it is further than $A$ from the rotation center. ...

0

You don't have to look at other frames of reference to find out if yours is an inertial frame. With respect to your frame of reference, that is using your cartesian coordinate axes and your clock, if you determine that Newton's first law is valid then yours is an inertial frame of reference. Let's consider two examples. (1) You are sitting inside a ...

1

This kind of question has a long and honorable history. As a young student, Einstein tried to imagine what an electromagnetic wave would look like from the point of view of a motorcyclist riding alongside it. But we now know, thanks to Einstein himself, that it really doesn't make sense to talk about such observers. The most straightforward argument is ...

1

That line will get Coriolis acceleration $$\vec{a} = -2 \vec{\Omega} \times \vec{v}$$ ($\Omega$ is the angular speed of the earth's rotation, with a direction pointing into the ground from the view of the south pole). As it's going across the pole, there's a right angle between $\Omega$ and $v$ and the absolute value will be simply $$a = 2\Omega v$$ and the ...

3

For both interpretations, the answer is 'yes' since force still acts in an opposite force on anything which has mass. As you accelerate, your velocity increases and therefore mass will increase. The increase in mass will bring about an opposite force. The greater the mass, the greater the inertia.

0

It depends on how you define inertia. http://en.wikipedia.org/wiki/Inertia#Interpretations. The answer to your question is 'yes' if we interpret inertia as p=mv, and no if we interpret it as F=ma.

0

An inertial reference frame is everything moving at the same velocity in the same direction under no acceleration (in the train case just assume the train is going a constant speed and ignore gravity). Your question about viewing a ball go up and down from edge-on versus-side on is really just a minor geometrical perspective difference. On a train, the ...

0

You could also define a LT as a transformation which transforms orthonormal basis into orthonormal basis (you have to exclude translations, since they don't belong to the Lorentz group).

1

You're not doing anything wrong, the objects will have different momenta in different reference frames. What should be the same in every reference frame is the forces acting on the objects during the collision. The laws of physics are the same in every reference frame, but not necessarily the numbers that go into the equations. By way of example, lets ...

1

The problem is that your frame of reference, if you put it in an object that is accelerating is not an inertial one; the discrepancies are due to inertial forces that you're not taking into account. Why don't you just observe things from a fixed, absolute, inertial reference frame, instead?

5

There can be at least two different flavors of paradoxes. In one, a result such as 2+2=5 is proved, and the problem must be either incorrect reasoning or a set of assumptions that was invalid. In the other type, exemplified by the EPR paradox, the correct result of an argument is so surprising that it seems like it must be a mistake. Based on the ...

2

I put my negative comment in the from of the answer. Here are the very basics of the simultaneity implications (or causes) of relativity: According to the special theory of relativity, it is impossible to say in an absolute sense whether two distinct events occur at the same time if those events are separated in space, such as a car crash in London ...

-1

The time wouldn't freeze. Instead, all events in the world will happen at the same time and place (from the viewpoint of the observer travelling at the light speed). It would be better to say that the world (i.e. space & time) would collapse into single point.

-5

Hibernation is one way to freeze time,that is to arrive at future date,the natural way to time travel. Linear or circular movement at very high speed is the scientific theory to reach future.

-2

Our visible universe is made up of 3 dimensions of space and 1 dimension of time. All objects in the universe exist in this space-time continuum. Space and time are not 2 separate entities irrelative of each other. Space and time are intimately united as one entity called spacetime. As mentioned earlier, all stationery objects experience their time in this ...

2

This is essentially the same as lurscher's answer, but from a different perspective. Special Relativity is often thought of as some kind of mystical force that acts on objects and stops them moving faster than light. This misconception is the reason for questions like this one. Special Relativity is actually just a prescription for telling us what events in ...

-2

The speed of light seems to be the undisputed speed limit of the universe, in relation to the fact that to travel faster than a massless photon is able to travel would not only be physically impossible because no object containing mass would be able to stand the blinding speed, even in the vacuum of space without atmosphere to create drag. Also, there is ...

4

in relation to anything else that can make such measurements. As the speed of light is universal, nothing can see any other massive field moving at the speed of light (which is reserved for massless fields) your 0.51 number suggests that you expect that naive addition of velocities holds when velocities approach the speed of light. This is wrong. Here is ...

0

We assume OP's question (v2) is the following: Given a null geodesic on a Lorentzian manifold, does there locally exist Fermi normal coordinates along the null geodesic? (Here the word 'locally' means in some tubular neighborhood.) The answer is Yes, see. e.g. Ref. 1. (As OP correctly notes, most textbooks deal only with Fermi normal coordinates ...

1

To add to Mark Eichenlaub's nice answer... Suppose that in the Euclidean plane, you have two people, $P$ and $P'$, located at the same point (or as near as possible), but they're facing in different directions. Each of them imagines the usual Cartesian coordinate axes, say with $x$-axis to the direction they're facing, which we'll call depth. Suppose also ...

0

What is the exact mechanism by which time dilates for a fast moving object? There's no intuitive explanation nor any other special mechanism to describe SR effects other than the unification of spacetime. The view is completely based on its postulates. There's no absoluteness in time. There's no preferred reference frame meaning that every observer ...

10

Your question is a natural one to ask, but it has no answer. It is a bit like asking by what mechanism the angles of a triangle always wind up adding to 180 degrees (in Euclidean geometry). There is no mechanism for that - no one is going around checking all the triangles to make sure their angles add up right. It is just a logical consequence of the theory ...

0

First of all, I think that you should formalise what a reference frame is. Some people say that it is the same thing as the coordinate system, but stated this way, it is something physically senceless. Somewhere I heard the following definition of a reference frame: A reference frame is an observer with a device that can measure the relative position of ...

0

I think it is , start running with an acceleration on earth such that it opposes your acceleration due to earth's rotation , and thus in net your acceleration will get 0 ,and you'll be an inertial reference frame . However , then obviously you'll see earth to be accelerating as you are inertial reference frame now .

0

I can't understand why you ask, whether we can create something which is totally mathematical and not some physical "thing". A reference frame is totally for our convenience to measure the parameters like position, time or orientation of some object relative to a co-ordinate system we've preferred. So, No - It's not possible in any known way. I suggest you ...

1

I might have misunderstood your question. If you mean, is there an absolute "motionless"? The answer is No, because all motion is relative. Inertial reference frames are reference frames that are not accelerating - two inertial reference frames move at a constant velocity with respect to each other. Whilst there is no absolute motion, there is absolute ...

1

It is General Relativity that changed our concept of space and time. Even special relativity assumes that time and space exist as coordinates even though it changes the metric with respect to the Galilean (Newtonian) relativity. As physics started to be rigorously mathematically formulated in the eighteenth century , space and time were considered as ...

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