\(_7^{14}N + \alpha \to _8^{17}O + _1^1p\)

Ta có: \(\overrightarrow {{v_O}} = \overrightarrow {{v_p}} \)

Áp dụng định luật bảo toàn động lượng: \(\overrightarrow {{P_t}} = \overrightarrow {{P_s}} \leftrightarrow {m_\alpha }\overrightarrow {{v_\alpha }} = {m_O}\overrightarrow {{v_O}} + {m_p}\overrightarrow {{v_p}} \)

\(\begin{array}{l}\overrightarrow {{v_O}} = \overrightarrow {{v_p}} \to {m_\alpha }\overrightarrow {{v_\alpha }} = \left( {{m_O} + {m_p}} \right)\overrightarrow {{v_O}} \\ \to \overrightarrow {{v_O}} = \overrightarrow {{v_p}} = \dfrac{{{m_\alpha }\overrightarrow {{v_\alpha }} }}{{{m_O} + {m_p}}}\end{array}\)

\(\left\{ \begin{array}{l}{{\rm{W}}_O} = \dfrac{1}{2}{m_O}v_O^2\\{{\rm{W}}_p} = \dfrac{1}{2}{m_p}v_p^2\end{array} \right. \to \left\{ \begin{array}{l}{{\rm{W}}_O} = \dfrac{{{m_O}{m_\alpha }}}{{{{\left( {{m_O} + {m_p}} \right)}^2}}}{{\rm{W}}_\alpha }\\{{\rm{W}}_p} = \dfrac{{{m_p}{m_\alpha }}}{{{{\left( {{m_O} + {m_p}} \right)}^2}}}{{\rm{W}}_\alpha }\end{array} \right. \to \left\{ \begin{array}{l}{{\rm{W}}_O} = 0,21{{\rm{W}}_\alpha }\\{{\rm{W}}_p} = 0,012{W_\alpha }\end{array} \right.\)

Mặt khác,

\(\begin{array}{l}\Delta E + {{\rm{W}}_\alpha } = {{\rm{W}}_O} + {{\rm{W}}_p}\\ \to \Delta E = {{\rm{W}}_O} + {{\rm{W}}_p} - {{\rm{W}}_\alpha } \leftrightarrow - 1,21 = 0,21{{\rm{W}}_\alpha } + 0,012{{\rm{W}}_\alpha } - {{\rm{W}}_\alpha }\\ \to {{\rm{W}}_\alpha } = 1,555(MeV)\end{array}\)

=> Động năng của hạt Oxi là: \({{\rm{W}}_O} = 0,21{W_\alpha } = 0,21.1,555 \approx 0,33MeV\)