Question

The length, breadth and height of a cuboidal tank are 150 cm, 120 cm and 110 cm respectively. The tank has $129600c{m}^3$ of water in it. 100 porous bricks each having dimensions $20cm\times 10cm\times 10$ cm are placed in the tank. Calculate the rise in the water level of the tank, if each brick absorbs $\frac{1}{10}$ of its own volume.

Answer 1

Volume of brick = $20\times 10\times 10=2000$ cc.
Volume of 100 bricks = 2,00,000 cc.
Hence, when 100 bricks, the water raises so that volume of displaced water = 2,00,000 cc. But bricks are porous and absorb 10% of its own volume. Hence, the volume of water displaced = $2,00,000\times 90$ % = 1,80,000 cc.
The dimensions of tank are $150\times 120\times 100$
Hence, the height to which water raises =$\frac{180000}{(150\times 120)}=\frac{180000}{18000}=10cm.$