Proton electric potential/ final speed calculation

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Homework Help Overview

The problem involves a proton moving through a uniform electric field, where participants are tasked with calculating the change in energy and final speed of the proton as it traverses a potential difference. The subject area includes concepts of electric potential, energy changes in electric fields, and kinematics.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss using equations related to work and potential difference to determine energy changes. There is confusion about the relevance of certain equations in the context of a uniform electric field. Some suggest using the relationship between potential difference and kinetic energy to find the final speed.

Discussion Status

The discussion is active, with participants exploring different approaches to the problem. Some guidance has been offered regarding the use of equations and the implications of the uniform electric field on the proton's motion. Multiple interpretations of the problem are being considered.

Contextual Notes

Participants are navigating the complexities of energy changes and kinematics in the context of a proton moving against an electric field. There is an emphasis on understanding the implications of the uniform field and the potential difference involved.

physicsstar26
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Homework Statement



A proton (q=+e, m= 1.67*10^-27 kg) traveling at 300 m/s enters a uniform electric region opposite to the field direction.
a.) find the change in the energy of the proton as it moves 2 m across a potential difference of 100kV in this field. Express answer in eV.
b) find the final speed of the proton in km/s


Homework Equations



a) W=q*V
V= k*q/r I'm confused as to how to approach this problem.
b) once you know V or the above answer do you just plug it into V= (1/2) mv^2/q?
thanks
 
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physicsstar26 said:

Homework Equations



a) W=q*V
V= k*q/r I'm confused as to how to approach this problem.
b) once you know V or the above answer do you just plug it into V= (1/2) mv^2/q?
thanks

What does your equation (a) represent? How will it relate to the change in (what?) energy of the proton?

As for the next equation, since the proton is in a *uniform* field, will that equation be useful? What does *it* represent?
 
for (a) would you just use Va-Vb= E* dl to find the potential difference?
 
physicsstar26 said:
for (a) would you just use Va-Vb= E* dl to find the potential difference?


Well, you can take that route to work out the force on and acceleration of the proton. That will let you answer (b), after which you can back-figure part (a).

Alternatively, you can use the potential difference to figure out the kinetic energy change of the proton, then work out part (b). Either approach requires about the same amount of calculation.
 
physicsstar26 said:

Homework Statement



A proton (q=+e, m= 1.67*10^-27 kg) traveling at 300 m/s enters a uniform electric region opposite to the field direction.

Ah, be careful in handling either the kinematics or energetics for this situation. What is the proton going to do in this field?
 

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