Buoyancy is the decrease in weight felt by an object when submerged in a fluid, caused by the upward buoyant force of the fluid. The buoyant force is equal to the weight of fluid displaced by the object. An object will float if its density is less than the fluid's density, sink if greater, and be neutrally buoyant if equal, neither floating nor sinking. Archimedes' principle states the buoyant force is equal to the weight of fluid displaced.

1. Buoyancy

2. Buoyancy Buoyancy: The decrease in weight (gravitational force) caused by the buoyant force. (example: floating in a swimming pool) Buoyant force: The upward force on an object produced by the surrounding fluid.

3. Buoyant force animation Buoyancy animation: buoyant force animation Density of water = 1g/ml So… Density > 1, the object sinks Density < 1, the object floats Density = 1, the object has neutral buoyancy. It neither floats nor sinks; it hovers in the middle.

4. Archimede’s Principle Calculating the Buoyant Force Archimede's Principle: The buoyant force acting on a submerged object is equal to the weight of the volume of fluid displaced by the object. ------------------------------------------------------

5. Density and Buoyancy of Fluids The same principles apply to fluids Example: During the recent oil spill, the oil floats to the surface and can be “vacuumed.” Oil Spill

6. Assignments Complete at home density of fluids lab Email photos /video and analysis questions and conclusion Density column