Aye, Aye Captain!
Engineer a “berry” awesome juice powered boat, and enjoy sailing the seven seas all month long!
Here is what you’ll need:
1 Styrofoam cup
1 Styrofoam bowl
1 Bendy straw
Tape or glue
Your favorite juice
Pool or tub filled with water
How to construct your boat:
1. Glue or tape the 2 styrofoam plates together face to face. The edges should meet.
2. Attach the bowl upside down to one of the plates using tape or glue.
3. Near the bottom cup, poke a hole just big enough to fit the straw through.
5. Stick the short end of the bendy straw through the hole in the cup. The longer end of the straw should point down.
6. When the glue dries (if you used it), decorate your boat.
7. Place your boat into the pool or tub, and add water to the cup. The boat should begin to glide across the water.
8. Once the water has emptied from the cup, fill the cup with your favorite juice.
9. Observe the boat’s speed differences when using water compared to using juice.
How does the boat work?
When you place liquid into a cup, it pushes on all sides of that cup. By poking a hole in the cup, you create an area in which the liquid can no longer push on. However, the water still pushes on the other areas of the cup, and this force propels the boat along the water until all of the water has left the cup.
Water molecules have an attraction to each other, called cohesion (the tendency of molecules to stick to one another), and that property gives water its’ surface tension. If you look closely at an area of water, such as a pond or bathtub, you can see a skin-like film across the surface of the water.
When you add juice the cup, and the juice comes out of the straw and into the pool or tub, it breaks the water’s surface tension. Since juice molecules are not the same as water molecules, they will not stick to one another. The breaking of the water’s surface tension will make the molecules pull away from each other, and anything on the surface will move with the molecules, therefore, making the boat glide faster!