# Homework Help: Relativistic Energy

1. Dec 9, 2008

### Aeighme

1. The problem statement, all variables and given/known data
A radium isotope decays to a radon isotope by emitting an α particle (a helium nucleus) according to the decay scheme 226Ra --> 222Rn + 4He. The masses of the atoms are 226.0254 u (226Ra), 222.0176 u (222Rn), and 4.0026 u (4He). What is the total kinetic energy of the decay products (in MeV)?

2. Relevant equations
E0=mc2
E=gamma*mc2
K=gamma*mc2-mc2
E=K+E0
1u=931.494 (MeV)/c2

3. The attempt at a solution
I really don't know what to do for this...

2. Dec 9, 2008

### Aeighme

This concept is confusing for me and once I understand this, it will make the rest of my problems much easier to solve.

3. Dec 9, 2008

### Lyuokdea

well...how much more massive is the input (radium), than the output (Radon and a Helium nucleus)....I'm not sure if you are confused by the notation, the 4He should be one helium nucleus with 4 nucleons.

~Lyuokdea

4. Dec 11, 2008

### malawi_glenn

calm down, wait more than 13minutes before bumping thread :-)

5. Dec 11, 2008

### Remo Aviron

<< complete solution deleted by berkeman >>

Last edited by a moderator: Dec 11, 2008