All surface assumed to be frictionless the horizontal force F that must be applied so that m1 and m2 do not move relative to m3 is :

Q: All surface assumed to be frictionless the horizontal force F that must be applied so that m1 and m2 do not move relative to m3 is :

(a) $(m_1 + m_2 + m_3) \frac{m_2 g}{m_1}$

(b) $(m_1 + m_2 ) \frac{m_2 g}{m_1}$

(c) $( m_2 + m_3) \frac{m_1 g}{m_2}$

(d) $(m_1 + m_3) \frac{m_1 g}{m_2}$