Density & Buoyancy

Density & Bouyancy

Definitions Bouyancy- The force that keeps you afloat is called bouyancy Density- the comparison of how much matter there is in a certain amount of space.

Density

Other information on density

Density is a comparison of how much matter there is in a certain space, matter is made up of molecules and atoms.

A key unit for density is g/cm3. Formula for solids is D = m/v = g/cm3 Formula for liquids is m/v = g/mLAlways write down the formula for density.

Buoyancy is the ability of an object to float. For the object to float it is determined by the bouyant force.

Bouyancy

There is a upward force in all fluids. Fluid pressure is strongest at the bottem of the box, causing a net upward force - the bouyant force.

Discovered by Archimedes

Fluid Pressure

Sink or Float?

Depends on two forces bouyancy and gravity.Gravity > BF = sink Gravity < BF = Float Gravity = BF = Neutral

To Measure BF.

Place object in water, look to see how much water displaces. Weigh the displaced waterBF= weight of displaced water Units of force= Newton (N)