Does anyone know the answer or how to solve this ?

a neutron in a reactor makes a elastic head on collision with the nucleus of an atom initially at rest. assume: the mass of the atomic nucleus is about 11.5 the mass of the neutron. what fraction of the nuetron's kinetic energy is transferred to the atomic nucleus?

if the initial kinetic energy of the neutron is 4.06 × 10^-13 j, find it's final kinetic energy. in units of j

[05.02] what is the best explanation of the kinetic molecular theory as it relates to the energy of the molecules in the states of matter? (1 point) the molecules in a gas have greater kinetic energy than those in a liquid, which in turn have greater kinetic energy than the molecules in a solid. kinetic energy cannot be created nor destroyed, and, as a result, all states of matter have the same kinetic energy. the molecules in a gas have greater kinetic energy; therefore, they are more tightly packed than the molecules in either a liquid or a solid. the molecules in gases and liquids, in constant motion, have greater kinetic energy than those in a solid, which do not move or vibrate because their position is fixed.