Proton or Electron: Who's Faster?

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Discussion Overview

The discussion revolves around the question of which particle, an electron or a proton, moves faster when they are allowed to accelerate towards each other from rest. The scope includes concepts of momentum, mass, and acceleration in a physics context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant notes that in the center of mass frame, the proton's much greater mass means the electron will be moving faster at the point of collision due to conservation of momentum.
  • Another participant provides relative mass values, indicating that the electron is significantly lighter than the proton, which supports the idea that it will be moving faster.
  • A claim is made that conservation of momentum implies the electron's speed is 1840 times that of the proton's speed.
  • One participant discusses the forces acting on both particles, suggesting that since they have the same charge, the electron experiences greater acceleration due to its lower mass, as described by Newton's second law (F = ma).
  • A later post introduces LaTeX formatting for equations, indicating a desire for clarity in mathematical expressions related to the discussion.

Areas of Agreement / Disagreement

Participants generally agree that the electron will be moving faster than the proton due to its lower mass and the implications of conservation of momentum. However, the exact relationship between their speeds and the factors influencing them is discussed without reaching a definitive consensus.

Contextual Notes

The discussion does not resolve the exact numerical relationship between the speeds of the electron and proton, and assumptions about the system's initial conditions and external influences are not fully detailed.

Cyto
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Hey there guys... I got a question for are you whiz's... Let's say you place an electron and proton a certain distance from each other and allow them to accelerate towards each other. Just before the collision, which is moving faster?
 
Last edited:
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In the original reference frame (both initially at rest), the center of mass (of the two particles) is very close to the proton, since it is almost 2000 times as massive. Once they start moving, the center of mass doesn't move. As a result the elctron is moving much faster than the proton when they collide. The velocities are in the inverse ratio of the masses - conservation of momentum.
 
relative masses:
mass of a proton = 1
mass of an electron = 1/1840


relative charges:
proton= +1
electron= -1


clearly the electron is far much lighter than the proton,so it will be moving faster.
 
Thanks for the number. Therefore conservation of momentum makes the electron speed 1840 times the proton speed.
 
On a simpler level, consider that the forces on each particle is the same, as they have the same charge. But the electron has less mass, so by:

F = ma
a = F/m: the electron undergoes much more acceleration.

Damn... still can't get hang of latex...
 
[tex]a = \frac{F}{m}[/tex]

Click my image, or quote my post, to see how it's done.

Or, if you want to be a purist, you can make your vectors bold.

[tex]\renewcommand{\vec}[1]{\mbox{\boldmath $ #1 $}}<br /> <br /> \vec{a} = \frac{\vec{F}}{m}[/tex]

Or, if that's not clear enough, you can use little arrows -- which is the default behavior for LaTeX's \vec command.

[tex]\vec{a} = \frac{\vec{F}}{m}[/tex]

- Warren
 

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