Density is mass per unit volume.
Density of an object determines if it floats or sinks.
Objects more dense than the fluid they are submerged in sink.
Objects less dense than the fluid they are submerged in float.
Physical Science - 8th grade
Density and Buoyancy
- All objects experience a buoyant force when immersed in a fluid. As a basis for understanding this concept:
- Students know density is mass per unit volume.
- Students know how to calculate the density of substances (regular and irregular solids and liquids) from measurements of mass and volume.
- Students know the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced.
- Students know how to predict whether an object will float or sink.
Prior knowledge & experience:
Ice Cube in Water and Rubbing Alcohol
What happens when you put an ice cube in water? (Drop ice cube in beaker filled with water)
-Ice cube floats.
Watch this again. (Drop ice cube in beaker filled with rubbing alcohol)
-Ice cube sinks!
Regular Soda versus Diet Soda
What happens when you take your cooler of drinks to the beach? As the ice melts in the cooler do the sodas float or sink?
Drop a regular soda into a large container of water and it will sink.
Then drop the same brand diet soda into the same container and it will float.
Photographs and Movies