# Find the speed of the alpha particle after the reaction

1. Aug 10, 2014

### student34

1. The problem statement, all variables and given/known data

For the nuclear reaction, 1 neutron (1/0n) + 10/5B → 7/3L + 4/2He (alpha particle) assume that the initial kinetic energy and momentum of the reacting particles are negligible. Calculate the speed of the alpha particle immediately after it leaves the reaction.

2. Relevant equations

E = mrestc^2

Ek = (mtotal (before) - mtotal (after))c^2

3. The attempt at a solution

I really have no idea because there is no change in mass that I can see, and that is all I had to look for with questions similar to these in this chapter.

2. Aug 11, 2014

### Simon Bridge

$\renewcommand{\e}[1]{\text{#1}} \e n_0^1 + \e B_5^{10} \to \e{Li}_3^7 + \e{He}_2^4$
Did you look up the masses or just go by the number of nucleons?

3. Aug 11, 2014

### student34

I only used the number of protons and neutrons. I can't think of any other reason why they would have a different mass.

4. Aug 11, 2014

### cpscdave

I'd check the masses out then :)

5. Aug 11, 2014

### Simon Bridge

Yep - go look up the masses :)
Write back with a list.

Consider: where does the "binding energy" of a nucleus come from?