The Candle Swing
intro
Materials:
- 2 cups
- 2 pins or needles
- A Sabbath candle (standard white candle)
- Matches
- Knife
- Tray or aluminum foil
What to do?
- Carefully carve the base of the candle to expose about 1 cm of the wick on both ends
- Insert two toothpicks at exactly the center of the candle, one on each side
- Spread aluminum foil on the table (to prevent wax from dripping on the table)
- Place two upside-down cups next to each other and position the candle between them
- Light the wicks at both ends of the candle
How does this happen?
When the toothpicks are inserted at the exact center of the candle, when we place the candle on the cups, it remains perfectly balanced. Once we light both ends, the wax begins to heat and melt. As wax drips from one end, it disrupts the balance, causing that side to rise.
The side that is now lower comes closer to the flame, causing the wax on this end to melt faster until a drop falls. Since both ends alternate in dropping wax, we observe a continuous rocking or swinging motion.
This fascinating demonstration shows Newton’s third law of motion (for every action, there is an equal and opposite reaction) and illustrates principles of balance, gravity, and energy conversion as heat transforms into mechanical motion.
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