## Essential University Physics: Volume 1 (4th Edition)

$v=.268 \ Mm/s$
We first use the equation for kinetic energy to find the speed of the alpha particle. Thus: $v = \sqrt{\frac{2K}{m}}= \sqrt{\frac{2(5.15\times10^6)}{4 \ amu}}$ We know that momentum is conserved, so it follows: $239v+4(\sqrt{\frac{2(5.15\times10^6)}{4 \ amu}})=0$ $v=.268 \ Mm/s$