Electrostatic Forces on Particles

1. May 27, 2008

DMac

[SOLVED] Electrostatic Forces on Particles

"An Astatine 219 nucleus and an alpha particle at a spacing of 1.5 x 10^-15 m are formed during alpha decay. If the initial velocity of the two particles is zero, calculate the ratio of their velocities."

I was thinking of making a ratio of their kinetic energy, but I'm not sure if that's simplifying the problem too much.

If I make a ratio, I get:
.5 x m1 x v1^2 : .5 x m2 x v2^2
...

v1
--- = sqrt [m2 / m1]
v2

Is this right?

2. May 27, 2008

gendou2

Seems right to me. Conservation of kinetic energy is a handy trick!

3. May 27, 2008

DMac

I'm just not sure if it can be done any other way....because I certainly cannot use force (since force varies with the distance, just like the gravitational potential well). So all I could think of was energy.

However, I'm particularly unsure because my manipulation basically equates the two kinetic energies; that is, the energy of the alpha particle is the same as that of the astatine particle.

4. May 28, 2008

gendou2

Yes, the energies are the same, but the velocities are different.
This is due to the different masses.