1. Problem statement i am trying to calculate the momentum and energy of the products in the reaction 7Be4 + e -----> 7Li3 + neutrino 2. Relavant equations p = mv mass of 7Be = 7.016929 u mass of 7Li = 7.016004 u 3. The attempt at a solution i know that after the electron capture, the neutrino and the daughter nucleas will move in opposite directions with the same momentum magnitude, and so form momentum coservation mv(Li) = mv(neutrino) but how do i go about findig the 'v' of Lithium in order to calculate its momentum, mv. the question does not give any info on 'v'. ? Do i even need the value of 'v' or not. So that i can then put that 'v' into the equation of finding the energy of the daughter nucleas as: 1/2 * m(Li)*v^2(Li) = ( m(neutrino)/m(Li) ) * E(neutrino) am i actually in the right path, i would greatly appreciate any directions?