Usaha dan Energi Pembahasan Soal 1

Gerak A - B

Hukum Kekekalan Energi

\begin{equation*}
\begin{split}
EM_1 & = EM_2 \\\\
EP_1 + EK_1 & = EP_2 + EK_2 \\\\
\cancel {m} \:.\: g \:.\: h_A + 0 & = 0 + \tfrac{1}{2} \:.\: \cancel {m} \:.\: v_B^2 \\\\
g \:.\: h_A & = \tfrac{1}{2} \:.\: v_B^2 \\\\
2 \:.\: g \:.\: h_A & = v_B^2 \\\\
2 \:.\: g \:.\: R \cos 37 & =  v_B^2
\end{split}
\end{equation*}

Gaya Normal di B

\begin{equation*}
\begin{split}
\sum F_{\text{ sentripetal}} & = m \:.\: \frac{v^2}{R} \\\\
N - mg \cos 37 & = m \:.\: \frac{2 \:.\: g \:.\: \cancel {R} \cos 37} {\cancel {R}} \\\\
N & = 3 \: mg \cos 37 \\\\
N & = 2,4 \: mg
\end{split}
\end{equation*}