Relativistic momentum and gamma factor - differential equation

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SUMMARY

The discussion focuses on deriving the force equations for a relativistic particle, specifically when the force is perpendicular and parallel to the particle's velocity. The equations are established as F=γm_0(dv/dt) for perpendicular force and F_x=m_0γ^3(dv_x/dt) for parallel force. The participant seeks clarification on the time derivative of the gamma factor, γ, and its dependence on velocity components. Additionally, the kinetic energy integral W = ∫F_xdx = m_0c^2(γ-1) is explored, with challenges in integrating the expression involving the square root of (1-v^2/c^2).

PREREQUISITES
  • Understanding of relativistic mechanics and the concept of gamma factor (γ).
  • Familiarity with differential equations and their applications in physics.
  • Knowledge of calculus, specifically integration techniques.
  • Basic principles of force and momentum in physics.
NEXT STEPS
  • Study the derivation of the time derivative of the gamma factor in relativistic contexts.
  • Learn about integrating functions involving square roots, particularly in the context of relativistic kinetic energy.
  • Explore the relationship between velocity components and gamma factor in relativistic motion.
  • Investigate hyperbolic functions and their applications in solving differential equations related to relativistic physics.
USEFUL FOR

Students and educators in physics, particularly those focusing on relativistic mechanics, as well as anyone looking to deepen their understanding of force and momentum in high-velocity scenarios.

kapitan90
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Homework Statement


I am supposed to show that the force on a relativistic particle when
a) it's perpendicular to particle's velocity is F=γm_0\frac{dv}{dt}
b) it's parallel to particle's velocity is F_x=m_0γ^3\frac{dv_x}{dt}

I may make use of the fact that \frac{dγ}{dt}=\frac{v_xγ^3}{c^2}*\frac{dv_x}{dt}
2. Relevant equation
I don't understand why \frac{dγ}{dt}is 0 in case a) (this follows from the last formula, but I don't understand it either), why do we use v_x instead of v which γ depends on ?
 
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I am also supposed to show that the kinetic energy of a particle accelerated from rest to v_xisW =∫F_xdx=m_0c^2(γ-1) but I am stuck with the integral∫ (1-v^2/c^2)^{-0.5} dx I tried to integrate it by parts and to use Wolfram, but it couldn't solve it either. Any ideas?
 
One problem at a time. First problem
Your formula for d(gamma)/dt is not quite right. Well, it's right for your scenario, but it's also confusing you. Try going over the time derivative again. Maybe first try to take the time derivative of the full momentum vector, and then analyze the two cases when it comes time. Then to predict a future complication, don't be worried if you have a v^2/c^2, you can rewrite as some common terms.

Okay, because I don't know when I'll check back, I'll give you a clue to the second problem, it starts with hyper and ends with trig.
 
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