Why is the Electron's Momentum Higher in Special Relativity?

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Homework Help Overview

The discussion revolves around understanding why the momentum of an electron, as described by special relativity, is greater than that predicted by Newtonian mechanics. The context involves concepts of mass, momentum, and the implications of relativistic speeds.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between mass and momentum at high speeds, with some suggesting that the increase in momentum is due to the increase in effective mass. Others question the clarity of the conditions under which special relativity applies, particularly regarding speeds not close to the speed of light.

Discussion Status

There is an ongoing exploration of the statements regarding momentum and mass in special relativity. Some participants affirm the correctness of certain statements while also raising questions about the clarity of others. The discussion reflects a mix of agreement on the principles involved and a desire for deeper understanding of the conditions stated.

Contextual Notes

Participants note that the applicability of special relativity may be limited to high speeds, and there is a recognition that at lower speeds, relativistic effects can be negligible. This introduces a layer of complexity to the discussion regarding the assumptions made about mass and momentum.

JDiorio
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Homework Statement


Why is the value of the electron's momentum according to special relativity larger than that predicted by Newtonian mechanics?

A. At high speeds, the electron responds to forces and collisions as if its mass
were greater than the rest mass
B. At high speeds, the total momentum of two colliding particles is not conserved
C. Special relativity only applies at speeds close to the speed of light


Homework Equations


p= m(Vo)/sqrt(1-beta^2)


The Attempt at a Solution


I believe that the answer is A because as the velocity of an object approaches the speed of light, the momentum increases because its mass begins increase. So therefore at high speeds it would act as if its mass is greater than if it were at rest. Please let me know if this is the correct answer. Thank you
 
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you're correct, at high speeds it's mass energy is greater than that of it's rest mass, so it's mass (and therefore momentum) increases, also seen by E = \frac{mc^2}{root(1-B^2)}
 
JDiorio said:

Homework Statement


Why is the value of the electron's momentum according to special relativity larger than that predicted by Newtonian mechanics?

A. At high speeds, the electron responds to forces and collisions as if its mass
were greater than the rest mass
B. At high speeds, the total momentum of two colliding particles is not conserved
C. Special relativity only applies at speeds close to the speed of light


Homework Equations


p= m(Vo)/sqrt(1-beta^2)


The Attempt at a Solution




I believe that the answer is A because as the velocity of an object approaches the speed of light, the momentum increases because its mass begins increase. So therefore at high speeds it would act as if its mass is greater than if it were at rest. Please let me know if this is the correct answer. Thank you

Well it is true but there is something that is not fully clear here;

Statement C is also right, if an object is not close to the speed of light the change in its mass can be neglectible,it is just so little.But it is still appliable.So i guess the answer is A but in my opinion statement C should be clearer anyway...
 
thanks a lot for everyone's help!
 
Glad it worked out. I solved this by process of elimination; without thinking much about it B and C are false statements.
 

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