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Physics · WORK, ENERGY AND POWER
हिन्दीA fast neutron collides elastically and head-on with a stationary nucleus of mass number \( A \). The fraction of its initial kinetic energy retained by the neutron after the collision is:
Correct answer · Option 1
\( ( \frac{A-1}{A+1} )^2 \)
Explanation
The final velocity is \( v_{1f} = \frac{m_1 - m_2}{m_1 + m_2}v_i = \frac{1-A}{1+A}v_i \), so the retained fractional kinetic energy is \( f_1 = \frac{K_{1f}}{K_i} = ( \frac{A-1}{A+1} )^2 \).
