Matter Basics
What is mass?
The amount of matter in an object.
What makes an object float?
If the upward buoyant force is greater than its weight.
Why does oil float on water?
Why does oil float on water?
What is buoyancy?
The upward push of a fluid (liquid or gas) on an object.
What is volume?
The amount of space an object takes up.
What makes an object sink?
If its weight is greater than the buoyant force.
Why does hot air rise above cold air?
Hot air is less dense than cold air.
Why do you feel lighter in a swimming pool?
The water pushes upward on your body (buoyant force).
What is density?
How tightly packed matter is in a given space.
Why does a sponge float at first but sink after it fills with water?
The sponge starts less dense than water, but when it fills with water, it becomes denser and sinks.
Why do helium balloons float in air?
Helium is less dense than the air around it.
What did Archimedes discover about buoyancy?
The buoyant force is equal to the weight of the water displaced by the object.
How tightly packed matter is in a given space.
The rock — because its particles are packed more tightly.
A steel ship floats, but a solid chunk of steel sinks. Why?
The ship’s hollow shape traps air, making it less dense overall, but a solid chunk is too dense to float.
Why do ice cubes float in a drink?
Ice is less dense than liquid water.
How do submarines rise and sink?
They take in water to sink and fill tanks with air to rise.
Two balloons are the same size. One is filled with air and the other with water. Which is heavier and why?
The water balloon, because it has more mass in the same volume (higher density).
If you shaped a ball of clay into a boat, why would it float?
The boat shape spreads out the mass and displaces more water, increasing buoyancy.
What would happen if ice were denser than water?
Ice would sink, oceans would freeze from the bottom up, and life in water would change drastically.
In a liquid layering experiment with honey, water, and oil, which liquid would sink to the bottom and why?
Honey, because it has the highest density.