In order to save energy and reduce emissions, hollow bricks are widely used in buildings to replace solid bricks. As shown in the figure, the specification of a hollow brick with a mass of 3.6kg is 20cm × 15cm × 10cm, and the solid part of the brick accounts for 60% of the total volume Find: (1) the density of the brick material; (2) How many kilos of material can be saved in the production of each hollow brick compared with the solid brick of the same specification?
V = 20cm × 15cm × 10cm * 60% = 3000cc * 60% = 1800cc = 1.8 × 10 ^ - 3M & sup3; P = m / v = 3.6kg/1.8 × 10 ^ - 3M & sup3; = 2 × 10 ^ - 3M & sup3; V '= 3000cc * (1-60%) = 1.2 × 10 ^ - 3M & sup3; m = PV = 2 × 10 ^ - 3M & sup3; × 1.2 × 10 ^ - 3M & sup3; = 2.4kg