# Elastic Collision in Nuclear Reactors

Canadian nuclear reactors use heavy water moderators in which elastic collisions occur between the neutrons and deuterons of mass 2.0 u. What is the speed of a neutron, expressed as a fraction of its original speed, after a head-on, elastic collision with a deuteron which is initially at rest? What is its kinetic energy, expressed as a fraction of its original kinetic energy? How many such successive collisions will reduce the speed of a neutron to 1/59,000 of its original value?

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#### Solution Preview

mass of neutron m1 = 1 unit = 1*1.67*10^(-27) kg

mass of deutron m2 = 2 unit

initital velocity of neutron u1 = vo

initital velocity of deutron u2 = 0

By momentum law,

m1*u1 + m2*u2 = m1*v1 + m2*v2

1*vo + 0 = 1*v1 + ...

#### Solution Summary

This solution provides three answers with six steps of calculations. The law of conservation of momentum and Newton's experimental law are used.