Salted Popcorn

If you want to mix something up, you might put all the ingredients in a jar adn give the jar a good shake. The up-and-down movement should combine all the foods and evenly mix evertything together. That's what you'd think, but is that what really happens?

What you need

• 1 cup (250 ml) table salt
• 1/4 cup (60 ml) unpopped popcorn
• clear plastic jar with screw lid
• 4 or 5 large nuts such as brazil nuts
• 1/2 cup (125 ml) peanuts
• a few cashew nuts

What you do

1. Place the salt and popcorn in plastic container and tightly screw on the lid.
2. Roll the jar on the table so the salt and popcorn are really mixed together.
3. Stand the container on the table or counter and gently bang the container up and down. Watch what happens to the popcorn.
4. Empty the container. Try the same steps again with a jar filled with large and small nuts. What happens to the large nust when container is banged on the table?

What happend?

That's strange. the more you banged teh jar, the more the popcorn rose on teh top of the jar. Istead of mixing the tow ingredients, you actually sorted them. In fact, the salt gets packed togetehr under popcorn. When tapping loosens the salt so that it moves down and around the popcorn. When the salt gets underneath the popcorn, it packs together tightly and the salt crystals from a solid layer that the popcorn can't get through. After you given a few taps on the table, the popcorn has moved all the way to the top. The same thing happened with the larger and small nuts: the large nuts came to the surface.