# Direction of alpha particles/protons from isotope decay

1. Oct 5, 2016

### Vitani11

1. The problem statement, all variables and given/known data
A stationary B nucleus decays into two alpha particles and a proton, and the speed of the proton is found to be 6.0x10^6 m/s. What is the magnitude and direction of the velocities of the alpha particles with respect to the proton?

2. Relevant equations
Unnecessary

3. The attempt at a solution

Velocity has been found... what would the direction be? I was thinking opposite of the proton because they both have a positive charge but there is TWO alpha particles instead of one so wouldn't they be deflected at some angle instead of directly in front or behind the proton?

2. Oct 5, 2016

### haruspex

Just guessing here...
Suppose the particles leave with angle θ between the proton's path and that of each alpha particle, and the shape of the triangle they form is stable. I.e. their accelerations, velocities and distance moved stay in a fixed ratio. You have two unknowns, θ and that ratio. Considering the forces between them, you may be able to determine both.

3. Oct 5, 2016

### Vitani11

Using your guess... in this case do you think it would be okay to do the arctan of the alpha particles velocity over the protons velocity for theta? Theta would be the same for each alpha particle.

4. Oct 5, 2016

### haruspex

Consider momentum conservation.