Rotating Candle

Harness the power of physics to make a candle teeter-totter back and forth.

  1. Ages: 9 - 16

  2. <30 minutes

  3. Messy

  4. Grownup needed


Materials you'll need

Step-by-step tutorial

  • Step 1

    Gather your materials.

    Photo reference of how to complete step 1

  • Step 2

    Use a butter knife to expose the wick on the bottom of the candle. You may need a grownup to assist you.

    Photo reference of how to complete step 2

  • Step 3

    Straighten the paperclip.

    Photo reference of how to complete step 3

  • Step 4

    Poke a sewing pin through the middle of the candle. This is your pilot hole.

  • Factmagnifying icon graphic

    A pilot hole is a small hole drilled as a guide for the drilling of a larger hole.

  • Step 5

    Poke the straightened paper clip through the pilot hole. Make sure the candle is in the middle of the paper clip.

    Photo reference of how to complete step 5

  • Tip

    Having trouble? Heat the end of the paper clip before you push it through the candle. The candle and the paperclip should rotate as one. If they don’t, push a little wax into the hole to keep the paper clip in place.

  • Step 6

    Place two glasses about 1 ½ inches (3.175 cm) apart on a piece of tinfoil. This will catch the wax when you light the candle!

    Photo reference of how to complete step 6

  • Step 7

    Rest the paper clip across the glasses. Test it! Before you light the candle, make sure the candle doesn’t touch the table when it is straight up and down. If the candle is too long, use taller glasses or raise the glasses with something non flammable - like a tin can.

    Photo reference of how to complete step 7

  • Step 8

    Light both ends of the candle. What happens?

    Photo reference of how to complete step 8

  • Learn moremagnifying icon graphic

    This rotating candle kicks itself back and forth like two kids on a seesaw pushing off the ground. But how does it do that without any legs to kick? The secret is in the wax that drips off both ends.

    When you start, the candle is balanced. Because both sides weigh the same amount, the downward force from gravity is the same on both sides. With balanced forces, the candle doesn’t move.

    But then, one of the sides drips. The drip of wax weighs something, so losing it makes the dripping side lighter than the other side. Since the sides are unbalanced, gravity pulls more on the heavier side, making it move downward. That downward pull is like an upward kick to the other side of the candle, too.

    However, the two sides don't stay that way for long. Pretty quickly, the side that was pushed down melts off a big drop of wax, and that kicks the candle up to rotate back the way it came. 

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