- #1

- 591

- 12

## Homework Statement

A proton and an α -particle are projected with velocity v=√[itex]\frac{e^{2}}{4∏εmL}[/itex] each from infinity as shown.The perpendicular distance between their initial velocities is L .Let the distance of their closest approach be D .

Given .Find (8D/L - 5)^2

Details and assumptions

1)mass of proton=m,charge=+e

2)mass of α-particle=4m,charge=2e

## Homework Equations

## The Attempt at a Solution

As the particles are located at infinite distance from each other so I think dist.L will not matter much.

I tried to use reduced mass problem here.

Here reduced mass(M) =4m/5 let it be at infinite distance from origin O.

What should be the initial velocity of reduced mass here? Is it 2v.(I used 2v here)

Lat it be at a distance D from O after some time.

At D all its kinetic energy wiil be converted to potential energy so

Mv^2/2=k2e^2/R

On putting values and after doing some calcilations I got

4D=5L

I got the value of 25.Am I right?

I think I am not.

This is the link of figure.

d3pq38zxuosm5i.cloudfront.net/solvable/2676130fa9.92b5dbd0d6.O7DvUt.png

Last edited: