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\begin{aligned} \mathrm{KE}_{\text {int }}^{\prime} &=\frac{1}{2}(m+M) v^{2}=\frac{1}{2}(70.15 \mathrm{~kg})\left(7.48 \times 10^{-2} \mathrm{~m} / \mathrm{s}\right)^{2} \\ &=0.196 \mathrm{~J} \end{aligned}