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Make a ketchup packet sink on command!
Try this...
You’ll need:
- one ketchup packet (available in most restaurants)
- a one or two litre plastic bottle
- some water
Place the ketchup packet in a bowl or cup of water to see if it will float (for this experiment you will need a packet that only just floats).
Put the ketchup packet (complete with ketchup) in the bottle. Completely fill the bottle with water and close the lid tightly. Now squeeze the bottle hard and you can make the ketchup packet sink!
What’s happening?
There is a small air bubble trapped inside the ketchup packet. When you squeeze the bottle, the pressure inside it increases, which compresses the air inside the packet. This increases the density of the ketchup packet. When the air is compressed enough, the density of the packet will be greater than the density of the water in the bottle, and the packet will sink. When you let go of the bottle, the pressure inside the bottle decreases again so the air in the packet will expand. This causes the packet to rise back to the top.
