Ponyo Inspired :: Science Saturday

My kiddos love the anime movies of Hayao Miyazaki .  One of their favorite is Ponyo which was recently released onto DVD.  This delightful Japanese film follows the adventures of a 5-year-old boy, Sosuke, and his burgeoning friendship with Ponyo, a goldfish princess who desperately wants to become human. After running away from and then being recaptured by her strict father, Ponyo — with some help from Sosuke — becomes more determined than ever to make her dreams come true.

Ponyo’s magic brings “to life” one of Sosuke’s toys, a candle powered steam engine boat.  Like most boys, my little guy was fascinated by this boat and asked about it frequently after we had seen the film on the big screen.  To his surprise and delight, he received one in his Easter basket this year.
Inside the boat and extending out the stern, there is a little metal tubes.  This tube fills with water and when the water in the tube boils, the steam expands. This pushes the water out of the tube. The reaction pushes the boat forward.  As the steam continues to expand, it encounters the section of tubing that used to be full of water. This tubing is cold, and the steam condenses back into water. This causes a vacuum to form, which pulls more water back into the tubes.  As it does this, a little putt putt sound is generated.

You would expect that the water moving back into the tubing would cause the boat to go backwards. However, the water doesn’t get very far before it hits the end of the tube where the two streams of water meet each other. Any motion caused by the water being sucked into the tubes is reversed by the water hitting the front of the tube and pushing the boat forward again.

Buddy has been having a great time navigating the seas of our bathtub.  I know it will be the first thing he packs when we go camping this summer.  Little does he know that he is doing science!  🙂

Click here for instructions on how to build your own candle powered boat.  Here’s another, for more detailed descriptions, Pop Pop!