How Close Can a Proton Get to a Charged Sphere?

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Homework Help Overview

The discussion revolves around a physics problem involving a proton approaching a charged conducting sphere. The problem includes determining how close the proton can get to the sphere and calculating the voltage on the sphere's surface, with specific values provided for the proton's initial velocity, the sphere's radius, and its charge.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relevant equations, particularly considering energy conservation at the closest approach where the proton's velocity becomes zero. Questions arise regarding the electric potential at the proton's location and the necessary distance from the sphere's center to calculate it.

Discussion Status

Some participants have provided calculations for the electric potential and noted the relevance of the chosen equation. However, there is uncertainty regarding the distance of the proton from the sphere at the initial velocity, and one participant expresses concern about the lack of information and the upcoming test.

Contextual Notes

There is a noted absence of specific information about the distance of the proton from the center of the sphere at the time of its initial velocity, which may impact the calculations. Additionally, one participant mentions the pressure of an impending test, indicating time constraints in addressing the problem.

AnthroMecha
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Homework Statement



A proton is moving with an initial velocity of 6.28x10^5 m/s straight towards a large conducting
sphere of radius 85.2 cm. The sphere has a charge of 4.83 μC on it. Protons have a mass of
1.69x10^-27 kg.

a) Determine how close the proton can come to the surface of the sphere.
b) What is the voltage on the surface of the sphere?


Homework Equations



possibly 1/2mv^2=-qΔV

The Attempt at a Solution



Don't even know where to begin on this one
 
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AnthroMecha said:

Homework Statement



A proton is moving with an initial velocity of 6.28x10^5 m/s straight towards a large conducting
sphere of radius 85.2 cm. The sphere has a charge of 4.83 μC on it. Protons have a mass of
1.69x10^-27 kg.

a) Determine how close the proton can come to the surface of the sphere.
b) What is the voltage on the surface of the sphere?

Homework Equations



possibly 1/2mv^2=-qΔV

The Attempt at a Solution



Don't even know where to begin on this one
That's a good relevant equation, since at closest approach, the proton's velocity will be zero.

What is the electric potential at the location of the proton, due to the sphere?
 
SammyS said:
That's a good relevant equation, since at closest approach, the proton's velocity will be zero.

What is the electric potential at the location of the proton, due to the sphere?

I'm coming up with 50964.4V electric potential (I may be using the wrong equation).

I used V=(1/(4πε0))(q/r)

q=4.83μC, r=85.2cm
 
AnthroMecha said:
I'm coming up with 50964.4V electric potential (I may be using the wrong equation).

I used V=(1/(4πε0))(q/r)

q=4.83μC, r=85.2cm
That's good for part (b).

To find the potential due to the sphere at the location of the proton at the time its velocity is 6.28×105 m/s, you have to know how far the proton is from the center of the sphere at that time.

Did they give that quantity ?
 
SammyS said:
That's good for part (b).

To find the potential due to the sphere at the location of the proton at the time its velocity is 6.28×105 m/s, you have to know how far the proton is from the center of the sphere at that time.

Did they give that quantity ?

no. I'm wondering if it involves some sort of integral. I hope there's nothing like this one on the test, because I have to go take it in an hour, lol! I kind of procrastinated a bit on this one. :(
 

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