Archimedes' Principle
The most fundamental way to calculate buoyant force is using Archimedes' Principle:
* Buoyant force = Weight of the fluid displaced by the object
Here's how to break it down:
1. Determine the volume of the object submerged in the fluid. This is the volume of fluid that is displaced by the object.
2. Find the density of the fluid. You can look up the density of common fluids in tables or online.
3. Calculate the weight of the displaced fluid. Use the following formula:
* Weight of fluid = Density of fluid × Volume of fluid × Acceleration due to gravity (g = 9.8 m/s²)
Example:
Let's say you have a wooden block with a volume of 0.5 m³ submerged in water. The density of water is 1000 kg/m³.
1. Volume submerged: 0.5 m³
2. Density of water: 1000 kg/m³
3. Weight of displaced water: 1000 kg/m³ × 0.5 m³ × 9.8 m/s² = 4900 N
Therefore, the buoyant force acting on the wooden block is 4900 N.
Formula:
You can combine the above steps into a single formula:
Buoyant force (Fb) = ρf × Vsub × g
where:
* ρf = Density of the fluid
* Vsub = Volume of the object submerged in the fluid
* g = Acceleration due to gravity (9.8 m/s²)
Important Notes:
* If an object is floating, the buoyant force equals the object's weight.
* If an object is sinking, the buoyant force is less than the object's weight.
* This calculation assumes that the fluid is incompressible (its density doesn't change significantly with pressure).
