Answer:
46kg approx.
Explanation:
Given data
Density of concrete ρ_c=2200kg/m3
Mass of concrete m_c= 25kg
In water
[tex]F_{P2} + F_{app}-m_{cg}=0[/tex]
[tex]F_{app}=m_{cg}-F_{P2}[/tex]
Max Fapp = 25*g
Buoyancy force
[tex]F_{P2} = \rho WgV_c= \rho Wg\frac{\rho_c}{m_c}\\\\F_{ p2}= \rho Wg\frac{\rho_c}{m_c}[/tex]
[tex]25*g=m_cg- \rho W g\frac{mW}{\rho_c}= m_cg(1- \frac{\rho W}{\rho_c} )[/tex]
[tex]m_c=25( \frac{\rho_c}{\rho_c- \rho W} )[/tex]
substitute
[tex]m_c=25( \frac{2200}{2200- 1000} )\\\\m_c=25*1.833\\\\m_c=45.8[/tex]
=46kg approx.
