A 2L object with density 800 kg/m³ in water — does it float? What fraction is submerged?

800 < 1000, so it floats. Fraction = ρ_obj/ρ_fluid = 0.8 = 80%.

What is the buoyant force on a fully submerged 0.5m³ object in water?

F_b = 1000 × 0.5 × 9.8 = 4900 N.

A steel ship has mass 10,000 kg. What minimum hull volume is needed to float in seawater (1025 kg/m³)?

V_displaced = m/ρ_fluid = 10000/1025.

Pro 🔒~20 min

Buoyancy

Q: A 2L object with density 800 kg/m³ in water — does it float? What fraction is submerged?

800 < 1000, so it floats. Fraction = ρ_obj/ρ_fluid = 0.8 = 80%.

Q: What is the buoyant force on a fully submerged 0.5m³ object in water?

F_b = 1000 × 0.5 × 9.8 = 4900 N.

Q: A steel ship has mass 10,000 kg. What minimum hull volume is needed to float in seawater (1025 kg/m³)?

V_displaced = m/ρ_fluid = 10000/1025.

Explore Archimedes' Principle with different fluids

How it works

Buoyancy demonstrates a key principle: Archimedes' Principle states that a submerged object experiences an upward buoyant force equal to the weight of the fluid it displaces. Archimedes' Principle states that a submerged object experiences an upward buoyant force equal to the weight of the fluid it displaces. An object floats when its density is less than the fluid density. The principle explains why ships float despite being made of dense steel — their hollow shape displaces enough water to create sufficient buoyancy.

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Step-by-step

Adjust fluid and object densities.
Objects denser than the fluid sink; less dense objects float.
The force diagram shows weight vs. buoyant force.
Change the submerged fraction to see how buoyancy changes with partial submersion.

Key formulas

$F_b = \rho_{fluid} \cdot V_{displaced} \cdot g$ Buoyant force (Archimedes)
$\text{Float if } \rho_{object} < \rho_{fluid}$ Floating condition
$\text{Apparent weight} = W - F_b$ Apparent weight in fluid

Frequently asked questions

A 2L object with density 800 kg/m³ in water — does it float? What fraction is submerged?: 800 < 1000, so it floats. Fraction = ρ_obj/ρ_fluid = 0.8 = 80%.
What is the buoyant force on a fully submerged 0.5m³ object in water?: F_b = 1000 × 0.5 × 9.8 = 4900 N.
A steel ship has mass 10,000 kg. What minimum hull volume is needed to float in seawater (1025 kg/m³)?: V_displaced = m/ρ_fluid = 10000/1025.