A 10cm×10cm×10cm wood block with a density of 690 kg/m3 floats in water.

PART A

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

PART B

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

density of fresh water = 1000kg/m^3

ΣF = 0

- (ρwood)g(Vwood) + (ρwater)g(vwood) = 0

(vwood)/(Vwood) = (ρwood)/(ρwater)

(10 * 10 * h)/(10 * 10 * 10) = (690)/(1000)

h = 6.9 cm

the distance from the top of the block to the water is 10 - 6.9 = 3.1 cm

b) density of seawater is ρsea = 1030 kg/m³

(vwood)/(Vwood) = (ρwood)/(ρsea)

(10 * 10 * h')/(10 * 10 * 10) = (690)/(1030)

h = 6.699 cm

the distance from the top of the block to the water is 10 - 6.699 = 3.301 cm