Study Guide
Density and Buoyancy
Density
Density
- Density is the amount of matter in a given space. The formula for density is: Density = mass/volume.
- Students should know how to solve density, mass, and volume problems. KNOW THE EQUATIONS!
- Students should know the definitions for, units for, and how to find mass and volume.
- Know that the density of water is 1 g/mL (1 g/cm3). And that objects with a density less than 1.0 g/mL will float and objects with a density greater than 1.0 g/mL will sink.
Buoyancy
- Buoyancy is an upward force exerted by a fluid (a fluid is substance that flows – a liquid or a gas). It is always an UPWARD force.
- Students need to know Archimedes Principle and the principle of water displacement.
- Be able to explain, using buoyancy, why some objects float (like a heavy aircraft carrier) and some objects sink.
- If buoyant force is less than the weight of the object, the object will sink. If buoyant force is the same as the weight of the object, the object will float. (Buoyant force can’t be greater than the weight of the object because then the object would fly out of the water!)
