Colliding Particles using energy

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Homework Help Overview

The problem involves the interaction between an alpha particle and a proton, specifically focusing on their distance of closest approach when both are moving towards each other at a fraction of the speed of light. The context is rooted in nuclear physics and conservation laws.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply conservation of energy to find the distance of closest approach but questions their assumption that the final velocity is zero at that point. Other participants suggest reconsidering the hint about conserved quantities.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the assumptions made by the original poster. Guidance has been offered regarding the use of conservation laws, but no consensus has been reached.

Contextual Notes

The original poster is revising for a mid-term and is working from a previous assignment. There is an emphasis on understanding the problem rather than simply solving it, as indicated by the hints provided in the discussion.

seto6
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this question is from my previous assignment which was due 2 weeks back. just revising for mid-term not sure how to solve it. if someone explains it thoroughly it would be grate

Homework Statement


An alpha particle is a nucleus of Helium. It has twice the charge and four times the mass of the proton.

A proton and an alpha particle headed directly toward each other, had each initial speed of 3.9×10−3 c when they were far away.

Here, as is customary when describing processes involving nuclear targets, the speed is expressed as a fraction of c, the speed of light.

What is the distance of closest approach between the proton and the alpha particle?

Hint: There are two conserved quantities. Make use of both.



Homework Equations


U=Eqd or KqQ/r
K=1/2*(mv^2)

The Attempt at a Solution



.5m(v_i)^2 + Eq(d_i)= .5m(v_f)^2 + Eq(d_f)

where (V_f)=0 then i solved for (d_f)
and got the 1.87*10^-27 but the answer should be d_f=1.3*10^-13

could some 1 explain this to me and the reasoning! please
 
Last edited:
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You are assuming that V_f = 0. Make use of the hint that you were given.
 
this question is from my previous assignment which was due 2 weeks back. just revising for mid-term not sure how to solve it. if someone explains it thoroughly it would be grate
 
Why don't you make an attempt using the hints I just gave?
 
v_f is the final velocity , at minimum distance it can reach it will be zero.no?
 
seto6 said:
v_f is the final velocity , at minimum distance it can reach it will be zero.no?
No it won't. Use the hint that the problem gave you! What else is conserved besides energy?
 

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