Relativistic Definition and 1000 Threads

  1. Chris Miller

    B Relativistic simultaneity and symmetry problem

    With both their clocks synced at 00:00 (12 AM), spaceships A and B leave Earth in oposite directions, each at 17308257.5 m/sec (.57735027c), So the Lorentz factor of their relative velocity 259627884.49 m/sec (.866025404c) is 2. They travel in opposite directions at this velocity for 2 hours...
  2. H

    Velocity of a spacecraft at relativistic speed

    Homework Statement The closest star system is about 4.3 light years away from Earth. A spacetug is able to move a cargo ship at a constant force of g=9.8N/kg times the mass of the cargo ship for many years. Starting from rest, speed up the cargo ship until you're halfway to the nearest stars...
  3. C

    I Relativistic doppler shift and radar

    Consider at stationnary radar at the origin ##z=0## and a target (speed ##v##) moving along the ##z## axis and away from the radar. The radar is sending plane waves (frequency ##f_i##) to the target and they come back to the radar (the radar is then both an emitter and a receiver). I am...
  4. davidge

    I Relativistic relative velocity

    I'm interested in deriving the relativistic relative velocity of two particles moving near the speed of light. It turns out to be (with ##c = 1##) $$\frac{V^{(1)} - V^{(2)}}{1 - V^{(1)}V^{(2)}}$$ How should I approach to this problem? Maybe I should not think of particles at all, but instead...
  5. P

    A Four velocity with the Schwarzchild metric

    I am trying to solve the following problem but have gotten stuck. Consider a massive particle moving in the radial direction above the Earth, not necessarily on a geodesic, with instantaneous velocity v = dr/dt Both θ and φ can be taken as constant. Calculate the components of the...
  6. L

    What is the kinetic energy of a proton when neutron decays?

    Homework Statement What is the kinetic energy given to the proton in the decay of a neutron when: a) The electron has negligibly small kinetic energy b) The neutrino has negligibly small kinetic energy Homework Equations Q = (mn - mp - me - mv ) c2 = .782MeV Where T is kinetic energy, and...
  7. B

    Relativistic Momentum of photon

    Homework Statement How much work is required to accelerate a proton from rest up to a speed of 0.999c? What would be the momentum of this proton? Homework Equations p=γmv The Attempt at a Solution I got part A, which was the momentum. I found that to be 20.1 GeV. Now for part B I have to find...
  8. N

    I Relativistic charged particle in a constant uniform electric field

    I'm doing some special relativity exercises. I have to find $$x(t), v(t)$$ of a charged particle left at rest in $t=0$ in an external constant uniform electric field $$\vec{E}=E_{0} \hat{i}$$, then with that velocity I should find the Liénard–Wiechert radiated power. I will show you what I did...
  9. Thalooth Bin Khalid

    I Is it really possible that relativistic mass tends to reach infinity?

    I have seen at many places that if ever matter travels more faster than light, it's relativistic mass will reach nearly infinity. Some says it's the inertia, so very high energy is required to accelerate. But since it is traveling with the velocity above 3×10^8 m/s, i believe that the high...
  10. ElPimiento

    Puzzled by an equation for relativistic time difference....

    Homework Statement Suppose that A', B', and C' are at rest in frame S', which moves with respect to S at speed v in the +x direction. Let B' be located exactly midway between A' and C'. At t' = 0, a light flash occurs at B' and expands outward as a spherical wave. (A', B', and C' are all on...
  11. AishaGirl

    Can Light Wavelength Remain Unchanged at High Velocities?

    Homework Statement A probe is launched with velocity v=0.8c. A beacon emits a light with wavelength \lambda=500nm in its rest frame. Years later the probe is located by NASA using a telescope, When they measure the light they find the wavelength \lambda=500nm in their rest frame. Is this...
  12. B

    Gravity at relativistic speed

    Is it possible to find the speed increase due to gravity pull using the SR velocity addition formula or the calculator here? http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/einvel2.html Can you confirm that it is in accordance with GR formula? For example, if an asteroid is approaching the...
  13. W

    What is the Energy Released in a Nuclear Reaction?

    Homework Statement Homework EquationsThe Attempt at a Solution I'm not sure how to go about working on this. What I have tried is this line of reasoning: 1x4He needs 2x3He. 2x3He needs 2x(2H + p) Energy released is therefore 12.98 + 2(5.51) _+ 2(0.41) = 24.82 MeV. However, it does seem...
  14. bananabandana

    Can index swapping be applied to relativistic Lagrangian equations?

    Homework Statement Show that $$ \mathcal{L} = -\frac{1}{4}F^{\mu \nu}F_{\mu \nu} = - \frac{1}{2}\partial^{\mu}A^{\nu}(\partial_{\mu}A_{\nu}-\partial_{\nu}A_{\mu}) $$ Where $$ F^{\mu \nu} = \partial^{\mu}A^{\nu} - \partial^{\nu}A^{\mu} $$ Homework EquationsThe Attempt at a Solution $$...
  15. BitWiz

    B Measuring relativistic effects in a single frame

    Sorry if this is a dupe: An astronaut is in a windowless, sensorless starship that is drifting in an unknown location in space. There is an accelerometer aboard which reads zero. The astronaut turns on his ideal linear propulsion engine for one second, losing a negligible amount of propellant...
  16. H

    B Does the charge have a relativistic origin?

    Hello, Is there any evidence that shows a relationship between the angular frequency of the electron in hydrogen, and the charge-to-mass ratio, by the mean of the special relativity ? Looking to reading you
  17. R

    Pi meson decay (relativistic momentum)

    Homework Statement A charged π meson (rest mass = 273me) decays into a neutrino (zero rest mass) and a μ meson (rest mass = 207me). Find the kinetic energies of the neutrino and the mu meson. Homework Equations E = moγc2 K = mo(γ-1)c2 v = pc2/E p = moγv The Attempt at a Solution In the rest...
  18. michael879

    I Understanding Relativistic Ptcl Lagrangian: S1 vs. S2

    Can someone help me understand how the following two actions are related? S_1 = \int \left(-\dfrac{1}{2}mg_{\mu\nu}\dot{x}^\mu\dot{x}^\nu - U\right) d\tau S_2 = \int \left(-m\sqrt{g_{\mu\nu}\dot{x}^\mu\dot{x}^\nu} - U\right) d\tau Both of them lead to the correct geodesic equation as the...
  19. Cocoleia

    Relativistic kinetic energy and momentum

    Homework Statement A proton has a speed of 0.2c. Find the speed of an electron that has (a) the same kinetic energy as the proton, and (b) the same momentum as the proton. Homework Equations K=ϒmc^2-mc^2 The Attempt at a Solution This is what I did for the same kinetic energy part, but I...
  20. JulienB

    Relativistic E and B fields of an infinitely long wire

    Homework Statement Hi everybody! I have the following problem to solve: An infinitely long and thin straight wire carries a constant charge density ##\lambda## and moves at a constant relativistic speed ##\vec{v}## perpendicularly (##\beta##) and parallel (##\alpha##) to its axis. a)...
  21. RGalbiati

    Classical Good exercises book for relativistic electrodynamics

    Hi everyone. As the title says, I am looking for a good exercise book covering the topic of relativistic electrodynamics since the beginning. Even lecture notes from some universities would be great given that solved problems of increasing difficulty are provided. Do you know some book of this...
  22. T

    Relativistic rocket equation (intuitive derivation)

    Homework Statement In Newtonian mechanics, the rocket equation is derived by solving the simple differential equation -dm U = m dV, where U is the velocity of the expelled material relative to the rocket; a matter of conservation of momentum. In order to get the correct relativistic equation...
  23. Y

    How Can We Simplify the Algebra in Relativistic Elastic Collision Problems?

    Homework Statement Homework Equations et Em and pm be the energy and momentum of the mass m after the collision. Let p and p' be the momentum of mass M before and after the collision. From conservation of 4 momentum: \begin{bmatrix}E+m \\ p\end{bmatrix}=\begin{bmatrix}E_m+E' \\...
  24. phosgene

    Time taken for two relativistic particles to meet

    Homework Statement A particle P undergoes the hyperbolic motion x_{P}(t) = \frac{c}{a}(c^2 + a^2 t^2)^\frac{1}{2} along the x-axis of frame S, where c is the speed of light and a is a constant. A second particle, Q, undergoes the motion x_{Q}(t) = \frac{1}{2}ct + \frac{c^2}{a} and so...
  25. O

    Force on a relativistic particle

    Homework Statement [/B] A particle of rest mass ##m_0## is is caused to move along a line in such a way that its postion is $$x = \sqrt{b^2 + c^2 t^2} -b$$What force must be applied to the particle to produce this motion? 2. Homework Equations The velocity of the particle as seen from...
  26. charlesmartin14

    Help with derivation of two-body relativistic cross section

    Homework Statement I am trying to derive the 2 body cross section, as given in https://web2.ph.utexas.edu/~schwitte/PHY362L/QMnote.pdf dσ/dΩ Homework Equations I am stuck on d√s/dp=v where √s=(Ea+Eb)=E The Attempt at a Solution p=Ev (relativisitic energy-momentum relationship) √s=E...
  27. Z

    I Is mass conserved in relativistic collision?

    For a particle , E2 = (pc)2 + (moc2)2 and for a system of particle , (ΣE)2 = (Σpc)2 + (Σmoc2)2 so in that way before a collision, (ΣEi)2 = (Σpic)2 + (Σmoic2)2 and after , (ΣEf)2 = (Σpfc)2 + (Σmofc2)2 and as far as i know energy and momentum is conserved . so that means ΣEi=ΣEf and also Σpi=Σpf...
  28. P

    Directional Acceleration at Relativistic Speeds

    Homework Statement A particle flies along in the positive +x direction. It has a constant force F applied 30º clockwise to the x-axis. It is moving at .6 c. What is the angle of acceleration? Homework Equations a = F/(mγ3) The Attempt at a Solution [/B] I'm pretty sure I know how to do...
  29. Axidecimal

    V=? for Relativistic Mass,length contraction & time dilation

    Homework Statement Velocity Equations for Relativistic Mass,length contraction and time dilation. I was able to figure out one. This is not for homework. I want to learn these equations for future reference. Homework Equations The Attempt at a Solution Length Contraction : v = c...
  30. S

    Relativistic electron Moving through toroidal superconductor

    I understand the electron in the situation to be rapidly accelerated away from the torroid. If this is true, my question is: Will the electron emmit radiation following the synchrotron formula? Also, would the radiation travel through the torroid?
  31. Mister T

    Kinetic Energy and Momentum of a Relativistic Particle

    College-level introductory physics textbooks usually devote a chapter to special relativity. Peter J. Riggs in his article appearing in the February 2016 issue of The Physics Teacher (pp 80-82) derives a couple of expressions for the kinetic energy of a massive (as opposed to massless) particle...
  32. mangojuice14

    Relativistic electrons and positrons

    Homework Statement The question states that an electron and positron, each with rest mass energy of 511keV collide head on and create a proton and antiproton each with rest mass energy 938MeV. The question asks us to find the minimum kinetic energy of the electron and positron. Homework...
  33. A

    What is the speed of the centre of momentum frame in terms of c?

    Homework Statement A particle with mass m has speed 0.802c relative to inertial frame S. The particle collides with an identical particle at rest relative to frame S. Relative to S and in terms of c, what is the speed of a frame S' in which the total momentum of these particles is zero? This...
  34. A

    B Calculate Speed of Relativistic Rocket by Observation

    Hi, here are image of situation. We have observer in point A. He have clock and know distance L between points B and C. He is observing rocket travel from point B to point C at speed near light speed. Can he calculate the speed of rocket using v = L / TimeA? In rocket at point B here are...
  35. TheSodesa

    Escape Velocity of a Neutron Star: Relativistic Calculation

    Homework Statement Calculate the escape velocity on the surface of the neutron star in the previous problem (##m = \frac{2}{3} \cdot 2,1 \cdot M_{\odot}##; ##R = 15km##). Hint: Basic physics. Note, however, that the escape velocity is not going to be small when compared to the speed of light...
  36. petrushkagoogol

    I Compute Relativistic Velocities of Photons & Neutrinos

    Can we compute the relativistic velocities of 2 photons or 2 neutrinos ? :))
  37. Toby_phys

    Addition of masses in relativistic collision

    Really basic question: a particle, moving at speed u (u is fast enough for relativistic effects) with rest mass m0 collides with a stationary particle with rest mass m0. They coalesce to form a new particle of mass M (observer fame, not rest mass M) and move at speed v. find v in terms of y (y...
  38. TheSodesa

    A relativistic electron in a potential box

    Homework Statement In a potential box (##L = 1.00pm##) an electron moves at a relativistic speed, meaning it's momentum can't be expressed as ##P = \sqrt{2mE}##. a) Using the uncertainty principle, show that the speed is indeed relativistic b) Derive an expression for the allowed energy states...
  39. Isomorphism

    Particle decay: Relativistic or classical?

    This question was asked in an competitive exam in India. The relevant equations are momentum conservation in the classical sense and the 4 momentum conservation. My attempt: Classical momentum conservation would seem inaccurate since the kinetic energies are high. However, a straightforward...
  40. O

    I Relativistic Effect on Attraction between Moving Masses?

    Magnetism has be explained as a relativistic effect of moving charges. This was something we were shown in undergrad. Is there a similar effect when masses move relative to each other? 1. Is there any difference between the gravitational force between a single massive particle and a very...
  41. T

    Best Way to measure Relativistic Rocket Acceleration?

    Someday, mankind will be able to construct rockets that can move at relativistic speeds. The acceleration is given by ##a=\frac{F_0}{γ^3m_0}## ##F_0## can be easily measured by placing a force gauge on the rocket itself. The acceleration is much harder to measure, is has to be measured in a...
  42. J

    B Relativistic Simulation of Charged Particles: How a Physicist Would Go About It

    Supposed i wanted to do a relativistic simulation of charged point particles moving at different velocities and interacting with each other. My simulation would give me the x,y,z coordinates of each particle seen from an arbitrary observer's point of view, at a given t. The t given however, is...
  43. S

    I Relativistic rocket - where is the relativistic mass?

    A simple problem with a constant acceleration, ignoring mass of the fuel. The velocity of a rocket, which moves withe a constant acceleration g, is equal: v(t) = gt but I want to keep the const acceleration inside the rocket, not in the absolute sense. An acceleration has a dimension: L/T^2...
  44. S

    Recommended Books for Studying Relativistic Electrodynamics

    Hey guys, Can you please refer some good books to refer to in studying relativistic Electrodynamics (introductory parts), covering the Maxwell's equations in tensor form the L-W potentials and other aspects. FYI am just a beginner in relativistic Electrodynamics. Thanks for the help.
  45. ManicPIxie

    Relativistic Addition of Velocities

    This question comes from a previous years exam as practice for my upcoming. Homework Statement Two spaceships are launched from Earth, going in opposite directions. Eventually, both spaceships have a velocity of 0.75c (where c is the speed of light), each in their respective directions. A...
  46. Z

    A Relativistic generalization of Newton’s equation

    If say you have some scalar field, θ(x^u), where x^u represents the 4-vector coordinates of spacetime, and then the typical classical equation of motion, a = -∇θ, how would one go about 'generalizing' this to a relativistic version? Since F = ma, would you have to write it as d/dt (P^u)...
  47. bambambambambam

    B Philosophical Perspective: Need for Properties in a Relativistic Field?

    Philosophically speaking is there a need for a relativistic field to have no properties without an object on it? It seems like all throughout the history of mathematics there have been fields designed to describe the dynamics of specific particles, but isn't that necessarily a limit to their...
  48. K

    Relativistic Energy and Lorentz factor

    Homework Statement [/B] Two particles of rest mass m0 approach each other with equal and opposite velocity v, in a laboratory frame. What is the total energy of one particle as measured in the rest frame of the other? But the question gives a clue which reads "if (v/c)^2 = .5, then E =...
  49. J

    Resultant Velocities in 2D (Relativistic)

    Homework Statement Here's the question: http://i.imgur.com/zs130b3.png Homework Equations Just the usual Lorentz transform matrix etc. The Attempt at a Solution http://imgur.com/4Oipfu9 Now, the last line is clearly incorrect, since it tends towards infinite relative speed as v --> c. Of...
  50. D

    Modern Physics question -- an atom ejecting a relativistic electron

    Homework Statement . An atom at rest can undergo radioactive decay, ejecting an electron at a maximum speed of 0.5c. If the atom in a particle accelerator is observed to produce an electron traveling at 0.75c, at least how fast must the atom itself have been moving? Homework Equations u0 x...
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