Experiment
The liquid potato!
Potatoes always sink straight to the bottom of the pot or do they always do that?
Can you make a potato float?
You need:
- 2 large transparent bowls
- 2 dl. salt
- 2 liters of water
- 2 potatoes
This is what you do:
Pour 1 liter of water into each bowl.
Stir 2 dl of salt into one bowl (the other should be without salt)
Place a potato in each bowl.
Observe:
-
What happens to the potatoes?
Record your observations.
Explore further:
- Mix more or less salt in each glass. What happens to the potato?
- Use other liquids such as oil, vinegar, etc.
- Use sugar instead of salt. What happens to the potato then?
Record your observations.
What is going on?
Whether the potato floats or not depends on the density of the water in relation to the density of the potato. Density is how much something weighs relative to its size. When you salt the water, the density of the water increases and it becomes higher than the density of the potato. That's why the potato floats up!
In the same way, we float more easily when we bathe in salt water than in fresh water. If the water we bathe in had been even saltier, we would also have been lying and bobbing in the water surface like potatoes!
