Hukum kekekalan energi mekanik:
\begin{equation*}
\begin{split}
& EM_{(1)} = EM_{(2)} \\\\
& EP_{(1)} + EK_{(1)} = EP_{(2)} + EK_{(2)} \\\\
& EP_{(1)} + EK_{\text{translasi }(1)} + EK_{\text{rotasi }(1)} = EP_{(2)} + EK_{\text{translasi }(2)} + EK_{\text{rotasi }(2)} \\\\
& m \:.\: g \:.\: h_1 + \tfrac 12 \:.\: m \:.\: v_1^2 + \tfrac 12 \:.\: I \:.\: \omega_1^2 = m \:.\: g \:.\: h_2 + \tfrac 12 \:.\: m \:.\: v_2^2 + \tfrac 12 \:.\: I \:.\: \omega_2^2
\end{split}
\end{equation*}
Perlu diingat juga:
Momen inersia
(1) silinder pejal = \(\tfrac 12 mR^2\)
(2) bola pejal = \(\tfrac 25 mR^2\)
Hubungan antara \(v\) dan \(\omega\)
\(v = \omega \:.\: R\)