Balloons - the long ones work best; experiment with many types; tape; plastic straws cut in half; three12-foot pieces of string or yarn; paper clips
1. Thread three 12-foot pieces of string or yarn individually through three straws.
2. Create three “rocket launching stations” by tying the string so that you create a horizontal path, a vertical path, and a path with a 45-degree angle. You can tie the string to chairs, desks, etc. You might even attach one string to the ceiling and the floor! Make certain each string is taut.
3. Blow up a balloon, but don’t tie it.
4. Tape the balloon to the straw at the horizontal station, with the balloon opening facing opposite to the direction you want to balloon to travel.
5. Have the children make hypotheses (guesses) about what will happen when you release the end of the balloon. Why do they think these things will happen? Now, demonstrate the balloon rocket flight. What made the rocket go?
6. Split the class into three groups, one group at each station. Have them take turns trying to make the balloon rockets go. (They will probably need help blowing up the balloons and taping them onto the straws).
7. Once everyone has done this, have each group tape paper clips onto the inflated balloons. Do they go faster or slower? Why?
8. Have each group rotate to all three stations. As a group, discuss what happened at each of the three stations.
Now, explore! What other experiments can the children try with the balloon rockets? If they don’t think of experiments to try, ask them the following: What would happen if they taped another balloon (a booster rocket) to the first balloon; what do they think would happen if a balloon were taped at a right angle to the length of the straw on the horizontal string?
The air in the balloon is under pressure. When the neck of the balloon is opened, the natural elasticity of the balloon forces the air out, and the balloon shoots forward. This is a classic example of Newton’s Third Law: For every action, there is an equal and opposite reaction.
Why do the balloon rockets move more slowly when they have extra paper clips on them? Gravity is pulling all objects toward the surface of the Earth. The more mass something has, the heavier it is. Adding more weight (in this case paper clips) to the rockets means more force is needed to lift the weight.
Why are space rockets launched straight up? The goal is to lift the rocket into space as quickly as possible. The shortest distance into space is straight up. Flying out at any other angle means it takes more time, and therefore more force, to get the rocket away from the effects of Earth’s gravity.
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