Question

1. Will a 0.30 m × 0.30 m × 0.30 m empty copper (ρ_Cu = 8890 kg/m³) box float in water? The total mass of copper is 3.2 kg.

Answer 1

The average density of a box

$$\rho=\frac{m}{V}=\frac{3.2\rm \: kg}{(0.3\:\rm m)^3}=119\:\rm kg/m^3$$

Since

$$\rho<\rho_w=1000\;\rm kg/m^3$$

hence the box will float in water.