What you need:
A small plastic glass, two drinking straws, scissors, three paperclips and a drawing pin, two small candles that can fit into the straw, a matchbox a newspaper, a ruler
What to do:
1. Place a newspaper or mat on a table (something you don’t mind getting wax on).
2. Poke a hole through the bottom of the plastic glass using the scissors. Make the hole big enough so that the straw just passes through it.
3. Place the glass upside down on the newspaper and stick the straw through it like a flag post.
4. Measure the length of the second straw using the ruler and mark its centre. Poke a hole right through the centre using the drawing pin.
5. Unfold one of the paperclips as shown in the picture. Slide the open end of the clip through the holes you have just made in the straw. Rest the straw at the base of the bend.
6. Push the bent side of the clip into the first straw that is sticking out through the glass. Both the straws should look like a seesaw now.
7. Insert a candle (the wickless end) into each end of the second straw and use paperclips to hold them in place. Balance the seesaw by sliding the candles in or out of the second straw to equalize their weight.
8. Light one candle. Wait for a few seconds and then light the other one.
What happens:
Once both candles are lit, the candles start moving up and down in a seesaw swing. Gradually, this swing changes into a twirl and the candles begin to rotate.
Why?
In a normal playground seesaw, you use your legs to move yourself up and your weight to push yourself down. In case of the poor leg-less candles, their wax does the work for them.
Since you have lit one candle before the other, it starts to drip first, shedding wax. As the wax falls off that candle’s weight reduces and it rises up. Then, you light the second candle. Since this candle is angled downwards, its wax drips faster and it becomes lighter quicker. That means, it moves up. As the candles drip and shed wax they keep moving up and down according to the difference in their weights. Gradually, the swinging motion of the candles increases so much that they start rotating.
Had you lit both the candles at the exact same time, there would have been no seesawing because both candles would have lost wax at the same rate.
Picture Credit : Google
