\[\begin {array} {1 1} (a)\;\frac{(m_1-m_2)g}{(m_1+m_2)} & \quad (b)\;\frac{(m_1-m_2)g}{(m_1+m_2+I/l^2)}\\ (c)\;\frac{(m_1-m_2+I/R^2)}{(m_1+m_2)} & \quad (d)\;\frac{(m_1-m_2+I/R^2)}{(m_1+m_2)} \end {array}\]