Question

A block of wood of density 0.4 in the shape of a cube of 10cm edge floats in water. The lenght ofthe block above the water is

a) 2 cm
b) 4 cm
c) 6 cm
d) 8 cm

Answer 1

The length of the wood block that floats above water is 4 cm, this is determined by the principle of buoyancy and Archimedes' principle.

Step-by-step explanation:

The question relates to the concept of density and the principle of buoyancy. A block of wood with a density of 0.4 g/cm³ in the shape of a cube with an edge of 10 cm is floating in water. Since the density of the block is less than the density of water (1 g/cm³), the block will float. According to Archimedes' principle, the volume of water displaced by the submerged part of the block will have a mass equal to the mass of the block. Knowing that 60% of the block's volume is submerged, we can calculate that the length of the block above the water is 40% of its total height, which is 4 cm.

Answer 2

Using the principle of buoyancy, a wooden block with a density of 0.4 g/cm³ will have 60% of its height above water level, which is 6 cm, when it is floating.

Step-by-step explanation:

The question pertains to the concept of buoyancy and density in physics. When a block of wood with a density of 0.4 g/cm³, shaped as a cube with a 10 cm edge, floats in water, we can determine how much of the block will be above the water level by comparing the density of the block with that of water (1 g/cm³). Using Archimedes' principle, the fraction of the volume of the block submerged is equal to the ratio of the densities, in this case 0.4/1, which means 40% of the block is submerged and 60% is above water level. Given that the block is 10 cm tall, 60% of its height would be above water, which calculates to 6 cm.

This calculation is based on the fact that for the block to float, the weight of the water displaced by the submerged part of the block must be equal to the weight of the entire block. Since the block has a density less than water, it floats, and the extent to which it floats depends on its density relative to the water.