Lighter Than Air

By Sylvia, Danielle, Karen, Grace, and Santa

The topic of our investigation was the air pressure. We chose that topic because of a person named Marc Clayton who had given an assembly at our school called “Groovy Science.” One of the activities he shared with us involved a bottle shaped like a wine carafe, a balloon, and a burning piece of paper. He put the burning paper in the bottle and then put a small balloon on top. He explained that the air in the bottle was heating up, rose, and left the bottle by squeaking by the balloon. There was less air in the bottle and the weight of all the air above the bottle pushed the balloon into the bottle.

Even though we saw the balloon go into the bottle and heard the explanation, we still were wondering about the weight of air. Take your hand, for example. You don’t feel any air pushing on you. We were wondering: Does air really have weight? How much weight does it have?

Marc Clayton said we live at the bottom of “an ocean of air.” The earth is surrounded by air which weighs a lot. All the air in the atmosphere above us is pushing down on us. This is called air pressure. We did a little research and found that the weight of air on our skin is 14 pounds per square inch. That’s at sea level. If you go up a mountain it’s less.

To see if air really had weight, we did an experiment. First, we got all our materials ready (a meter stick, a balloon, some clay, string, tape, and a needle). Second, we tied the balloon that had a little strip of tape on it to the end of a meter stick. Next we stuck a ball of clay on the other end, making sure that the stick was balanced. Then we stuck a needle through the strip of tape and popped the balloon. Finally, we recorded the results. We did the experiment 3 times to make sure the results were the same.

We discovered that when the air left the balloon, the side of the stick with the balloon became lighter and went up. The side with the clay was heavier and went down. That proved that the air in the balloon had weight.

One of us is wondering if the results of our experiment would be different if we used different materials. Other students might want to try to find the strength of air. Another question we have is how does temperature affect air pressure? Also, we were thinking about gravity. How does gravity help us stay on the ground? We were also wondering about water pressure.