4.3.6—The upthrust acting on an object in a fluid using the equation F = ρgV

For a fully or partly immersed object, upthrust equals the weight of displaced fluid: F=ρ_fluid g V_displaced.

Use the fluid density and displaced volume, not the object’s total volume unless it is fully submerged. Compare the result with object weight.

Displacing 2.0×10⁻³ m³ of water gives F≈19.6 N at g=9.8 m s⁻².

Upthrust depends on displaced volume and fluid density, not directly on the object’s material or mass.