Calculating Speed of Electron after 50keV Work

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Homework Help Overview

The problem involves calculating the speed of an electron that starts from rest after a total work of 50 keV is done on it. The context includes concepts from relativistic energy and particle physics.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to convert the work done into total energy and apply the relativistic energy equation. They express confusion over obtaining a negative value when solving for speed.

Discussion Status

Some participants have provided guidance on including the rest mass energy in the total energy calculation. The original poster acknowledges this input and indicates a successful resolution to their issue.

Contextual Notes

The discussion highlights the importance of considering both the work done and the rest mass energy in relativistic calculations. The initial setup and assumptions are under scrutiny, particularly regarding the treatment of energy contributions.

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Homework Statement


what is the speed of en electro, initially at rest,if a total work of 50keV is done on it?
1eV=1.6*10-19j me=9.11*10-31kg

Homework Equations


relastic energy equaltion.


The Attempt at a Solution



i converted the total work to total energy

Etotal=8*10-15

then i set Etotal=(mc2)/(1-(v/c)2)1/2
when i try solving it i keep getting sqrt of a negative #
could someone tell me where I am going wrong
 
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You have to include the rest mass as part of the total energy, not just the work done on the particle
 
oh i see thanks!
let me see if it works
 
yeah it works thanks again !
 

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