Video Description -- Build a Sail
In this activity, you'll be building a sailboat out of a cup and tissue paper.
Materials Needed:
1 Foam cup
1 sheet of tissue paper (or gift wrap paper)
1 straw
1 pair of scissors
1 roll of tape
Procedure:
1) Tape your straw to the bottom of your cup. Your cup will be upside-down in our completed sail creation. Make sure to tape your straw so that the ends hang off.
2) Cut/tear off two square sails from your tissue paper. Make sure the sails are the same size. Experiment: Does the size of the sail matter?
3) Tape your sail to the straw (one side of the square).
4) Tape the bottom side of the sail to the cup. Make sure you give the sail some slack to catch some air. Experiment: How much slack should you give the sail? Hint: Use math to calculate how much surface area the sail takes up.
5) Blow on your sails or use a fan to make your cup go forward.
6) (Optional) Make a path for your sail to travel through. You can turn it into a game and see whose sail cup goes the furthest (or fastest).
Science
The tissue paper increases air resistance. When air hits the sail, the force of the wind will blow the sail forward. Try making only one sail on your cup and see what happens when you blow on it. Having a sail on either side raises the surface area of the sails (more air resistance) and helps keep the cup steady and not turn in a circle. How do you think real boats manage not to turn in a circle? Part of the answer is due to the resistance of water. Your cup relies on friction to keep it from moving in a circle. Since friction relies on the weight of the cup (which is not that much) and on how the table rubs against the cup, the cup is easy to turn. Real boats use the resistance of water to balance the forces and keep them going in their direction. The resistance of water is higher than of air. Imagine trying to swing your arm underwater as compared to air. In the water, your arm moves much slower since water is heavier.
Негізгі бет Sci-Tech Labs: Build a Sail (cup version)
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