Question

A 10cm×10cm×10cm wood block with a density of 730 kg/m3 floats in water.

a: What is the distance from the top of the block to the water if the water is fresh?

b: If it's seawater? Suppose that ρ=1030kg/m3.

Answer 1

a) In the density of water , p = 1000 Kg/m^3

let the distance from the top of block is x

weight of block = Buoyant force

730 * 0.10^3 * 9.8 = 1000 * 9.8 * 0.10^2 * (0.10 - x)

solving for x

x = 0.027 m = 2.7 cm

the distance from the top of block to water is 2.7 cm

b)

in seawater

let the distance from the top of block is x

weight of block = Buoyant force

730 * 0.10^3 * 9.8 = 1030 * 9.8 * 0.10^2 * (0.10 - x)

solving for x

x = 0.0291 m = 2.91 cm

the distance from the top of block to water is 2.91 cm