Physics · WORK, ENERGY AND POWER

In a nuclear reactor, heavy water (\( \text{D}_2\text{O} \)) is preferred over ordinary water as a moderator because deuterons have a mass close to that of a neutron. In a head-on elastic collision of a neutron with a stationary deuteron (\( m_d \approx 2 m_n \)), the percentage of the neutron's initial kinetic energy transferred to the deuteron is approximately:

1. A
   \( 88.9\% \)
2. B
   \( 50.0\% \)
3. C
   \( 71.6\% \)
4. D
   \( 11.1\% \)