- #1
STAii
- 327
- 1
In relativity, when it comes to calculating the beta factor, what frame of reference are we supposed to use to measure the speed of the object ?
Calculating Beta Factor: Frame of Reference?
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Discussion Overview
The discussion centers around the calculation of the beta factor in the context of relativity, specifically regarding the appropriate frame of reference to use when measuring the speed of an object. It explores theoretical implications and conceptual understanding of speed measurements in different inertial frames.
Discussion Character
- Conceptual clarification
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant questions which frame of reference should be used to measure the speed of an object when calculating the beta factor in relativity.
- Another participant suggests that any frame of reference can be used as long as consistency is maintained, mentioning common choices like the lab frame or center-of-momentum frame.
- A participant presents a scenario comparing two frames of reference, one stationary and the other moving at 0.8c, raising a conflict in perceived speeds of an object moving at 0.9c.
- In response, a participant points out that the speed of light is invariant across all inertial frames and emphasizes the need for Lorentz transformations to resolve the perceived discrepancies in speed.
Areas of Agreement / Disagreement
Participants express differing views on the implications of speed measurements in various frames of reference, with no consensus reached on the correct interpretation of the scenario presented.
Contextual Notes
The discussion highlights the importance of Lorentz transformations and the invariance of the speed of light, but does not resolve the specific confusion regarding the perceived speeds in different frames.
- #2
damgo
Whichever you want, as long as you're consistent.
Typically you start by picking a useful frame of reference - the lab frame, or the center-of-momentum frame, for example - and do all your calculations in that. If you want to switch to another frame, you have to Lorentz transform everything (or better yet, just use invariants!).
Typically you start by picking a useful frame of reference - the lab frame, or the center-of-momentum frame, for example - and do all your calculations in that. If you want to switch to another frame, you have to Lorentz transform everything (or better yet, just use invariants!).
- #3
STAii
- 327
- 1
Umm ...
So suppose i was comparing what i see in two frames of reference.
Let's asuume that the first frame of reference is not moving.
The second frame of reference is moving at 0.8c (with the direction of the body in subject) comparing to the frist frame of reference.
Now our body is moving at 0.8c comparing to the first frame of reference.
An observer in the first frame of reference thinks that the object can only speed up for the amount of 0.2c (cause otherwise the object will reach the speed of light).
While the observer in the second frame of reference thinks that the object can still speed up with the amount of 1c.
Let's suppose that the object actually speeded up for 0.9c, the observer in the first frame of reference will see that the object is moving in the speed of 1.7c which is impossible, while the observer in the second frame of reference will see the object moving at 0.8c which is possible !
So which one of them is right ? (or where did i go wrong ?)
So suppose i was comparing what i see in two frames of reference.
Let's asuume that the first frame of reference is not moving.
The second frame of reference is moving at 0.8c (with the direction of the body in subject) comparing to the frist frame of reference.
Now our body is moving at 0.8c comparing to the first frame of reference.
An observer in the first frame of reference thinks that the object can only speed up for the amount of 0.2c (cause otherwise the object will reach the speed of light).
While the observer in the second frame of reference thinks that the object can still speed up with the amount of 1c.
Let's suppose that the object actually speeded up for 0.9c, the observer in the first frame of reference will see that the object is moving in the speed of 1.7c which is impossible, while the observer in the second frame of reference will see the object moving at 0.8c which is possible !
So which one of them is right ? (or where did i go wrong ?)
- #4
Mulder
- 54
- 1
Just there?
.'c's the same in all inertial frames. Then you'd have to use the Lorentz transformations to work out it's new speed in a different reference frame.
Last edited:
- #5
STAii
- 327
- 1
Ah ...
Right, i got it now.
Thanks.
Right, i got it now.
Thanks.
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