October 2014

Frankenstein’s Hand (10/1/14)

MATERIALS:

  • 3 Tablespoons vinegar
  • 2 teaspoons baking soda
  • Rubber gloves
  • Wide-mouthed drinking glass or jar

INSTRUCTIONS:

  1. Pour the vinegar into the glass.
  2. Sprinkle the baking soda inside of the glove, and shake the powder into the fingers.
  3. Carefully stretch the glove around the lip of the glass while making sure the baking soda stays in the fingers. The glove should fit snugly around the glass.
  4. Pull the glove upright by its fingertips and gently shake the baking soda into the glass.
  5. Watch as Frankenstein’s hand comes alive!

HOW DOES IT WORK?

Baking soda is a chemical base, which strongly reacts with the acetic acid of the vinegar. One of the by-products of this reaction is carbon dioxide gas, which increases the pressure inside of the container. As more gas is produced, the pressure increases and pushes through the weaker surface (the rubber glove), causing the glove to inflate.

Screaming Balloons

MATERIALS:

  • Balloons
  • 1/4″ Hex nuts

INSTRUCTIONS:

  1. Squeeze the hex nut through the mouth of the balloon. Make sure the hex nut goes all the way into the balloon so there is no danger of it being sucked out when blowing up the balloon.
  2. Blow up the balloon, and tie it off. Do not overinflate the balloon, because it might pop!
  3. Swirl the balloon in a circular motion. The hex nut may bounce around at first, but soon it will begin rolling around inside the balloon. What is that awful noise?!
  4. Once the hex nut begins spinning, steadily hold the balloon and watch the hex nut spin around and around.

HOW DOES IT WORK?

The hex nut spins inside the balloon due to something called centripetal force. Centripetal force is the inward force on a body that causes it to move in a circular path. It is a “center-seeking” force. If we tried the screaming balloon experiment in space, the hex nut would continue spinning, but since we live on Earth, gravity will eventually bring the spinning to a halt. The screaming sound is made by the sides of the hex nut vibrating against the inside wall of the balloon.

NOW TRY THIS!

Try experimenting with other objects in place of the hex nut, like coins or marbles!