$F_{A1} = d_{nước} . V_{1} $
$= d_{nước} . \dfrac{m_1}{D}$
$F_{A2} = d_{nước} . V_{2} $
$= d_{nước} . \dfrac{m_2}{D}(1)$
Thay $m_2 = 2m_1$ vào $(1)$
$⇒ F_{A2} = d_{nước} . \dfrac{2m_1}{D}$
Lấy $F_{A1} : F_{A2}$ , ta có :
$\dfrac{F_{A1}}{F_{A2}} = \dfrac{ d_{nước} . \dfrac{m_1}{D}}{d_{nước} . \dfrac{2m_1}{D}}$
$\dfrac{F_{A1}}{F_{A2}} = \dfrac{1}{2}$
$⇒ F_{A2} = 2F_{A1}$