This floating lantern is a simple and fun way to brighten up your night. It only requires cheap items that can be found around the house. Follow these quick and easy instructions to create your own!!!
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Step 1: Materials List
- 1 clear plastic garbage bag
- Birthday candles
- Matches or lighter
Step 2: Building It
1. Cut 3-4 of the birthday candles in half (for a total of 6-8), shave them down so each candle has a good wick
2. Cut the foil into a square of 5x5 inches
3. Fold up each side of the foil square so the wax does not spill out
4. Use the matches/lighter to melt the ends of the candles, use the melted wax to stick the candles to the foil
5. Take 3 straws and connect them (putting one inside the other), make the length of the straws slightly shorter than the width of the bag (make 2)
6. Place one giant straw across the opening of the bag, taping it to the edges of the bag
7. Place the other giant straw perpendicular to the other having them cross in the center and tape it to the edges, make sure the bag is tight
8. Tape the foil with candles onto the center of the straws so the candles are pointing up towards the closed end of the bag
9. (Optional) Tie a string to one of the straws if you do not want it to float away
10. Hold the tip of the bag and light the candles
11. Release the bag after it completely fills up with hot air
Step 3: Physics Explanation
The lantern floats because physics. The use of hot air creates buoyancy which allows the fire lantern to rise. The candles on the foil heats the air inside of the large bag, this heated air generates lift by way of a buoyant force. The air inside the bag is less dense than the air surrounding the bag. The difference in density causes the lantern to lift off the ground due to the buoyant force created by the surrounding air. This follows Archimedes' principal which states that any object that is suspended in a fluid is acted upon by an upward buoyant force equal to the weight of the fluid displaced by the object. This principal is also applicable to objects in air, such as the fire lantern.
Step 4: Test Results
The first time we made the fire lantern it was not as successful as we had hope. Even though the bag floated, it did not get that high off of the ground and it quickly started to fall back down. For our next lantern we used a larger bag and more candles. This allowed the bag to contain even more hot air and with more candles, more hot air was produced. With the second trial, the bag floated much higher and never started to fall back to the ground (we had to use the string to pull it back).
Both of our trials were successful, however we found the best result was with a larger bag and more candles.