Gravity pulls all things together, but do they always make impact? Try this and amaze your friends.
Materials:
Key ring full of keys
Long shoelace
Pencil
What You Do:
Remove one key from the key ring. Tie it to one end of the shoelace, and tie the key ring (with the other keys still on it) to the other end.
Drape the string over the pencil—held parallel to the floor. The key ring should hang down about 1 inch below the pencil. Hold the key in your other hand.
Let go of the key. What happens? Do it again, watching the path of the key very carefully. Wow!
What’s going on? The key to this trick is energy. There are two different types of energy at work. Energy of motion is kinetic energy. Stored energy is called potential energy. When both the key ring and the key are stationary, they have potential energy. The key ring has more potential energy than the key because it has more mass. When you let go of the single key, it falls a long distance, building up momentum and speed as it travels, so it has a lot of kinetic energy. The key actually has more kinetic energy than the key ring and winds itself around the pencil. After a couple of turns around the pencil, the friction is so great that the key ring stops falling.
The science fair is quickly approaching! Look for registration slips to come home mid-March. Workshops begin on 21 March during lunch recesses Mondays, Wednesdays and Fridays. Want to help? We’d love to have you; contact Amy Oliver at amyroliver@gmail.com.
Materials:
Key ring full of keys
Long shoelace
Pencil
What You Do:
Remove one key from the key ring. Tie it to one end of the shoelace, and tie the key ring (with the other keys still on it) to the other end.
Drape the string over the pencil—held parallel to the floor. The key ring should hang down about 1 inch below the pencil. Hold the key in your other hand.
Let go of the key. What happens? Do it again, watching the path of the key very carefully. Wow!
What’s going on? The key to this trick is energy. There are two different types of energy at work. Energy of motion is kinetic energy. Stored energy is called potential energy. When both the key ring and the key are stationary, they have potential energy. The key ring has more potential energy than the key because it has more mass. When you let go of the single key, it falls a long distance, building up momentum and speed as it travels, so it has a lot of kinetic energy. The key actually has more kinetic energy than the key ring and winds itself around the pencil. After a couple of turns around the pencil, the friction is so great that the key ring stops falling.
The science fair is quickly approaching! Look for registration slips to come home mid-March. Workshops begin on 21 March during lunch recesses Mondays, Wednesdays and Fridays. Want to help? We’d love to have you; contact Amy Oliver at amyroliver@gmail.com.
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