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Fluids Formula

What is Archimedes' Principle?

Any object fully or partially submerged in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

Formula: F_b = \rho V g

Plain-English Meaning

Any object fully or partially submerged in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

Mechanics questions usually become easier once you identify whether the problem is about force balance, kinematics, energy, or conservation.

Deeper Explanation

Any object fully or partially submerged in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid.

Worked Example

Problem: A 0.002 m³ wooden block is fully submerged in water (ρ = 1000 kg/m³). Find the buoyant force.

  • F_b = ρVg
  • F_b = 1000 × 0.002 × 9.8
  • F_b = 19.6 N

Result: 19.6 N

At A Glance

Category: Fluids

Levels covered:

Best use: Start with the formula meaning, then move to the worked example and quiz so the equation turns into a tool instead of a memorised line.