All Questions
Tagged with speed-of-light velocity
107
questions
0
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3
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134
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Faster than light is possible? [duplicate]
I know that some particles can go near or more than half the speed of light. So, say we shoot two particles in opposite directions at more than half the speed of light. Say one is moving at 50% the ...
- 11
0
votes
1
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90
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Question about the norm of the four-velocity being equal to $c$
On the way to the Einstein equation we derived the four-velocity:
$$u^\mu=(c,v^k)$$ with $v^k$ being the 3-velocity, which can can be very low ($
|v|<<c$).
However, the square of the four ...
- 157
1
vote
1
answer
108
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Relativistic Velocity-addition formula adds a scalar to a vector?
Sorry if this is a stupid question.
The formula for relativistic Velocity-addition is
$u = (v + u') / (1 + (vu'/c^2))$
It seems that v, v', u, and u' are vectors, while c is a scalar.
But 1 seems to ...
- 855
2
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An interpretation of special relativity? [closed]
Consider a 4-dimensional space $\mathrm{S}$ in which all objects move at the same speed $c_S$ but in different directions. For the objects A and B that move in directions $\overrightarrow{u_A}$ and $\...
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1
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111
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Components of velocity 3-vector of light in spherical coordinates
The components of the velocity 3-vector of a light ray in cartesian coordinates can be found given a polar angle and azimuthal angle as follows:
$$
v_x = ||c|| \sin (\theta_0) \cos (\phi_0) \\
v_y = ||...
- 181
-1
votes
1
answer
66
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Sub-LightSpeed travel according to special relativity vs AP physics
For background, I'm a high school physics Student, and I was recently looking at special relativity out of personal interest, and I read a summarized statement "Time slows down as your approach ...
- 101
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53
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Question about theory of relativity [duplicate]
If you were running at a constant speed towards a light that is coming towards you and an other light was following you, from your perspective how is it possible that both lights go at the same speed....
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If a photon travelled in the opposite direction of another photon [duplicate]
If a photon travels in the opposite direction as another photon, then what is the speed of the second photon relative to the first. Is it 2 times the speed of light? Also what if two photons travelled ...
- 329
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25
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Does only the space region movement due universe expansion affect the possibility of viewing a star?
My question is maybe simple and easy to answer because the intrinsic speed of the star affects only the final frequency of observed light but are there any tricks about the combination of object ...
- 467
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28
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Special Relativity and Light [duplicate]
I just started learning about relativity in my physics class and would like some help understanding the concepts.
My question is imagine two objects start emitting light and are 1 lightyear away from ...
- 61
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3
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97
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Why is the speed of near speed of light moving particles not over the speed of light?
I've been looking for an answer to this question for a while now and I've seen the mathematical explanation
$$Vr=[V1+V2]/[1+V1*V2/c²]$$
I understand that the result cannot be greater than $c$ because ...
-4
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1
answer
52
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Is it possible to rotate object as fast as the linear velocity of point on surface become greater than speed of light?
Is it possible? Or the rotation also cause the increasing of the object mass and energy needed for acceleration?
- 768
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1
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42
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Making use of principles concerning relative and absolute velocity, can we move an object at a velocity that is greater than light?
I am new to physics, so please do not get angry if this is a stupid question.
First, let's imagine that we are sometime in the future where we have an extremely fast spaceship which is travelling in ...
- 101
9
votes
6
answers
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Can we measure the one-way speed of anything at all? [duplicate]
I know the one-way speed of light question has been exhausted, and I'm sorry for the naive question, but I would like to understand one thing. Can we measure the one-way speed of anything at all? If ...
- 109
0
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1
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79
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Relativity and speed of light [duplicate]
This might be a stupid question but anyway here it goes.
Let's say that I move towards a friend of mine at 75% of $c$ relative to the earth. Then, he moves towards me at the same velocity.
When we ...
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