Answer:
5
Explanation:
Volume of raft, [tex]v_r= 2\times 2\times 0.1= 0.4 m^{3}[/tex]
Density of raft, [tex]\rho_r=\frac {m_r}{v_r}=\frac {20}{0.4}=50 Kg/m^{3}[/tex]
Total weight= Buoyant force
Assuming n number of friends weighing 65 Kg then
(20+55+65n)g= Buoyant force
Buoyant force will be given by multiplying density of water by volume by acceleration due to gravity
[tex](75+65n)g=0.4m^{3}\times 1000 Kg/m^{3}\times g[/tex]
g is on both sides so they cancel
75+65n=400
65n=400-75=325
[tex]n=\frac {325}{65}=5[/tex]
Therefore, 5 friends each weighing maximum of 65 Kg can go with you on one trip
