(a) Assume that a neutron traveling at 3.00(103) km/s strikes the nucleus of a motionless 11Na23 atom in a reactor core. The collision causes the neutron to recoil elastically, and it travels backward along exactly the same path it traveled as it approached the atom. Calculate the velocity of the neutron after the collision. (b) Perform the same calculation for a 3.00(103) km/s neutron striking a 3Li7 atom nucleus. Based on your answers from these two calculations, which metal would perform better for use as coolant in a LMFBR where high neutron velocity is preferred