Notes

Density is basically how much “stuff” is packed into a particular volume. It’s a comparison between an object’s mass and its volume. Remember the all-important equation: density = mass ÷ volume. Based on this equation, if the weight (or mass) of something increases but the volume stays the same, then density goes up. Likewise, if the mass decreases but the volume stays the same, then density goes down. Lighter liquids (like water or vegetable oil) are less dense than heavier liquids (like honey or corn syrup) so they float on top of the heavier liquids. The same amount of two different liquids you used in the container will have different densities because they have different masses. The liquids that weigh more (a higher density) will sink below the liquids that weigh less (a lower density).

To test this, you might want to set up a sensitive kitchen scale and weigh each volume of the liquids that you added to the column. Make sure that you weigh identical volumes of each liquid. You should find that the weights of the liquids correspond to each different layer of liquid. For example, the honey will weigh more than the dish soap. By weighing the same volume (e.g. ¼ cup, 60 ml) of these liquids, you will find that density and weight are closely related.

By convention, plain water has a density of 1.0 and that’s measured in g/cm3 or g/ml. So, a cubic centimeter of water has a mass of 1 gram and fills 1 milliliter of volume. If a substance has a density less than 1.0 g/cm3, it floats on water and one with a density more than 1.0 g/cm3, it sinks in water. The numbers below are based on data from manufacturers for each item. Since each manufacturer has its own “secret” formula, densities may vary slightly from brand to brand for the same product but these are pretty close.

Material Density (g/cm3)
Honey 1.42
Pancake Syrup 1.37
Light Corn Syrup 1.33
Dish Soap 1.06
Milk 1.03
Water 1.00
Ice Cube 0.92
Vegetable Oil 0.92
Baby Oil 0.83
The same rule for “sink or float” goes for the small objects that you dropped into your density column. The metal bolt is more dense than all of the liquids in the column and therefore sinks directly to the bottom. Less dense objects will float on individual layers up the column. For instance, the plastic beads are more dense than the vegetable oil and everything above it but less dense than the water and everything below it. This makes the beads settle on top of the water. The Ping-Pong ball is the least dense of it all and floats on top.

TAKE IT FURTHER