# Math Help - Another physics question

1. ## Another physics question

Gold atom has mass of 3.3 * 10^-25 kg and is at rest. It emits an alpha particle of mass 6.6 * 10^-27 kg. As the alpha particle is emitted, teh gold atom becomes an iridium isotope (assume this mass is difference of mass of gold atom adn that of the alpha particle). Alpha particle has speed of 3.4*10^6 m/s.

Find the speed of the iridium isotope after emission process.

hmmm......equation?

2. Originally Posted by beetz
Gold atom has mass of 3.3 * 10^-25 kg and is at rest. It emits an alpha particle of mass 6.6 * 10^-27 kg. As the alpha particle is emitted, teh gold atom becomes an iridium isotope (assume this mass is difference of mass of gold atom adn that of the alpha particle). Alpha particle has speed of 3.4*10^6 m/s.

Find the speed of the iridium isotope after emission process.

hmmm......equation?
Conservation of linear momentum! Before distintegration momentum is zero

So after the momentum of the iridium is in the oposite direction to that of
the alpha particle and of the same magnitude, so:

$v_i \times 3.24~10^{-25}= 3.4~10^6 \times 6.6 ~ 10^{-27}$

where $v_i$ is the speed of the iridium atom.

RonL