Question

A block of wood of volume 30 cm3 floats in water with 20 cm3 of its volume immersed. Calculate:
(i) the density and
(ii) the weight of the block of wood

Answer 1

Density of the wooden block = 1.5 g/cm3

Weight of the block = 45 g

Explanation:

Volume of wood = 30 cm3

Volume of water displaced = Volume of wood immersed = 20 cm3

(i) Volume of wood outside water = 30 - 20 = 10 cm3

Volume of immersed part of body / Volume of the body = density of body / density of liquid

30 / 20 = x / 1

x = 1.5 g/cm3

Density of the wooden block = 1.5 g/cm3

(ii) Density = mass / volume

1.5 = mass / 30

Mass of the wooden block = 30 * 1.5 = 45 g