In nuclear reactors, subatomic particles called neutrons are slowed down by allowing them to collide with the atoms of a moderator material, such as carbon atoms, which are 12 times as massive as neutrons.
(a) In a head-on elastic collision with a carbon atom, what percentage of a neutron’s energy is lost?
(b) If the neutron has an initial speed of 1.5 x 107 m/s, what will be its speed after collision?