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Is an empty cup ever truly empty? No, it’s filled with air!
While it might be invisible, air is matter too. In this week’s Saturday Science experiment, courtesy of Wonders of our World, your kiddos will discover how air takes up space.
Materials
- 2 plastic cups
- Scissors
- 2 paper towels or tissues
- Double-sided tape
- Large beaker (1000 mL) or large pail
- Water
Process:
- Ball up a small piece of paper towel or tissue.
- Using the double-sided tape, attach it to the inside bottom of the plastic cup without a hole.
- Fill the pail of water or beaker approximately half full.
- Hold the bottom of the plastic cup and push it into the water with the open end of the cup pointing down into the water.
- Pull the cup out of the water. What happened to the paper towel or tissue?
- Now, have an adult carefully cut a small hole into the bottom of the other plastic cup.
- Ball up another small piece of paper towel or tissue and use the double-sided tape to attach it to the inside bottom of the cup with the hole.
- Hold the bottom of the plastic cup with the hole and push it into the water with the open end of the cup pointing down into the water.
- Pull the cup out of the water. What happened to the paper towel or tissue?
Summary
Was there a difference in the condition of each paper towel? Did the paper towel or tissue in the cup without a hole stay dry?
Wonders of our World explains that this happens because two types of matter cannot occupy the same space simultaneously. When the paper towel or tissue is added to the cup, the remainder of the cup continues to be filled with air. When the cup is submerged, the air compresses and some water fills that space. Without anywhere else for the air to go, it stops, and the compressed air becomes a barrier between the tissue and the water. When you add a hole to the cup, the air can escape, which means the cup fills with water and the paper towel or tissue gets wet.
Want more Saturday Science? See all of our at-home activities on the blog or Pinterest.
