Is the buoyant force greater than, less than, or equal to, the weight of

the objects below?

Fig. 1

Fig. 2

Fig. 3Less Than

Greater Than

Equal To

ReviewReview Density Buoyancy

Liquids Gases

Density AnomalyDensity Anomaly Hydrogen bond - when the (+) side of an H2O molecule attracts the (-) side of another H2O molecule

Liquid HLiquid H22OO Hydrogen bond

Density AnomalyDensity Anomaly As H2O cools off, the

hydrogen bonds become stronger

“ice” crystals formRegular

repeating arrangement

of atoms

Solid H2O“ice”

Water Ice

Density AnomalyDensity Anomaly As ice forms, its volume increases

But its mass stays the same

Density AnomalyDensity Anomaly When the volume goes up,

but the mass stays the same, the density goes down

Why does ice float?Why does ice float? Solid H2O (ice) is less dense than liquid H2O (water)

Ice = .9 g/cm3

Water = 1 g/cm3

Lake Superior froze over

completely in 1996