1. Momentum Problem: Make sure first to derive the equation necessary for 1-D elastic problem 8.49 -- Moderators. Canadian nuclear reactors use heavy water moderators in which elastic collisions occur between the neutrons and deuterons of mass 2.0 u (see Example 8.11 in Section 8.4). (a) What is the speed of a neutron, expressed as a fraction of its original speed, after a head-on, elastic collision with a deuteron that is initially at rest? (b) What is its kinetic energy, expressed as a fraction of its original kinetic energy? (0) How many such successive collisions will reduce the speed of a neutron to 1 / 59,000 of its original value