Why does it work?
Heat expands water. The firelighter flame heats the water inside the tubing which then pushes out of the tubes as a tiny bit of steam and heated water, producing a small amount of force to send the boat forwards. This shows that the idea that objects will move in the opposite direction to a pushing force...think Newton's 3rd Law of Motion which states for every action there is an equal and opposite reaction.
The expelled water out of the tubing creates a temporary low pressure area within the tubing coil. Any remaining steam inside the coiled tube condenses back into liquid water, further reducing the pressure. The water from the tub is pushed into the copper tubing by the surrounding air pressure... which is then be heated and the cycle repeats!
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