Special relativity (A.P. French 7.5)

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SUMMARY

The discussion focuses on solving a problem related to elastic collisions in special relativity, specifically involving a particle of rest mass m colliding with a stationary particle of rest mass M. The objective is to express the recoil and scattering angles in terms of the zero-momentum system angles and demonstrate that the results align with non-relativistic physics when the velocity v is much less than the speed of light c. Key equations involve the relativistic energy-momentum relation and the application of the binomial theorem for simplification.

PREREQUISITES
  • Understanding of special relativity concepts, particularly elastic collisions.
  • Familiarity with the energy-momentum relation, specifically (mc^2)/(1-(v/c)^2)^1/2.
  • Knowledge of the center-of-mass (COM) frame and lab frame transformations.
  • Proficiency in using the binomial theorem for approximations in physics.
NEXT STEPS
  • Study the derivation of the energy-momentum relation in special relativity.
  • Learn about transformations between the center-of-mass frame and the lab frame in collision problems.
  • Explore the application of the binomial theorem in physics for simplifying expressions.
  • Review non-relativistic limits of relativistic equations to understand the transition between the two regimes.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone studying special relativity, particularly those focusing on collision dynamics and energy-momentum relationships.

ladybeetle
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Homework Statement



A particle of rest mass m and velocity v collides elastically with a stationary particle of rest mass M. Express the recoil and scattering angels in terms of the corresponding angles in the zero-momentum system. Show that your answers reduce to the non-relativistic ones if v<<c


Homework Equations



I think I have to show that (mc^2)/(1-(v/c)^2)^1/2 reduces to .5mv^2 by using the binomial theorem when v<<c. since momentum is related to kinetic energy.

The Attempt at a Solution



(not clear how to do it though) Please help me!
 
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That's not what the question is asking you to do. In the center-of-mass system, say the particle with mass m scatters at an angle of ##\theta'##. What happens to the other particle? Now what does this collision look like as seen in the lab frame? What angle ##\theta## in the lab frame corresponds to the angle ##\theta'## in the COM frame?

Once you figure that out, you're supposed to show it reduces to the non-relativistic equivalents when v<<c.
 

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