All Questions
16 questions
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Regarding motion [closed]
I am conducting a thoughtful experiment
involving a train that accelerates at 10 m/s^2
. The train has a long passage of
12 m, and I am standing in that passage. If I jump up straight and remain in ...
user437229
0
votes
1
answer
133
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Velocity of Separation and Relative Velocity
I have some problems in understanding a concept, which has been used in the problem in the picture:
I don't understand what are we actually using to solve this question. Are we using relative ...
0
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1
answer
83
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How to find the coordinates for a worldline with $y=z=0$ that experiences constant acceleration?
I'm studying some lecture notes on special relativity and at some point one considers an inertial system in which a particle has $4$-velocity and $4$-acceleration given by
$$U = (c\frac{dt}{ds}, \frac{...
- 123
3
votes
1
answer
2k
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Proof of Lorentz invariant phase space factor
I was going through the following proof of Lorentz invariant Phase space (in Modern Particle Physics by Mark Thomson).
Could someone please help me understand how the equation in the box is valid? If ...
- 129
1
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2
answers
2k
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What is the maximum deflection angle of a pendulum in a car, when the car, initially at rest, accelerates suddenly? [closed]
I was doing Kleppner-D.-Kolenkow-R.J. and I came across the following problem:-
A pendulum is tied vertically to a car at rest, the car suddenly accelerates at a rate A. Find the maximum angle of ...
- 127
0
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0
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53
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Energy and momentum conservation equations for frame moving at speed $v$
A particle of rest mass $M$, while at rest in the laboratory, decays into a particle of mass $m$ and speed $v$, and a photon of frequency $f$ moving in opposite direction.
I want to look at this ...
- 83
2
votes
3
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511
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Four-vector of a proton as seen from the rest frame of another [closed]
I have a question regarding the four-vector of two protons. My task is to determine the four-vector of one proton as seen from the rest frame of the other.
I'm having a hard time understanding ...
- 121
0
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1
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193
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Derivation of simple Lorentz boost identity, $dp'_z/dp_z$
Given a Lorentz boost in the $z$-direction, in natural units we can write
$$p'_z = \gamma(p_z+\beta E)\,,\;\;\;\;\;E' = \gamma(E+\beta p_z)\,.$$
In Peskins & Schroeder's Introduction to QFT, p. ...
- 145
1
vote
1
answer
167
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Writing source four velocity for Lorentz boosted frame
I am trying to derive the source four velocity for Lorentz boosted frame. If the source four velocity for rest frame is denoted as $U^{\alpha} = (1, \bar 0)$, then how do I write this $U^{\alpha}$ for ...
- 149
1
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3
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811
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Ship' smoke velocity?
I am studying mechanics from MIT 2.003. In HW problem "which I solved wrong" they stated that:
An important fact is that the smoke travels with the wind at the velocity of the wind
In this problem ...
- 201
1
vote
1
answer
105
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Change in frequency of light clock due to to acceleration
The problem statement:
A light-clock (a photon travelling between two mirrors) has proper length l and moves longitudinally through an inertial frame with proper acceleration $\alpha$ (ignore any ...
- 23
0
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1
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91
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Kinetic energy in different frames [duplicate]
I have an electric bike moved by a battery. I am at a train station with two friends. A flat train car platform passes by at $1 m/s$. The friend #1 jumps on it while the friend #2 remains at the ...
- 12.9k
0
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3
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77
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Reference Frames
I observe two cars approaching each other from opposite directions and measure as 40 mph and 30 mph, respectively. How fast is the 40 mph car moving according to the driver in the 30 mph car? ...
- 19
1
vote
1
answer
392
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A fast object (0.8c) getting overtaken by another fast object (0.9c): why don't times agree?
I'm trying to work on an exercise in Wolfgang Rindler's book "Introduction to Special Relativity" and I'm stuck on the following exercise:
Two particles move along the x-axis of S at velocities 0....
- 237
3
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1
answer
216
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Special relativity kinematics problem [closed]
I have this problem in SR kinematics.
a spaceship travels near earth at c/2. it shoots off a light-ray at 45deg to its direction of travel (measured in its own ref frame). What is this angle in the ...
- 31
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1
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4k
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Finding the total energy in centre of mass frame
I'm working through a problem in a special relativity textbook (Woodhouse) and I'm having some difficulty.
I have to show that if I have a particle of rest mass $M$, total energy $E$ colliding with a ...
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