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Our PBL Project is called the Bernoulli Principle. This project is based on Bernoulli's discovery that moving water results in less pressure than still water and water will move to where there is less pressure. Our project shows how this principle affects the air around us. There are many demonstrations we will be exploring, but our primary demonstration shows that the manipulation of air by a leaf blower can cause an object to defy gravity.
Driving Question: How is it possible to suspend the beach ball in air?
Materials: Electric Leaf Blower, Extension Cord, Beach Ball.
Procedure
Plug the Electric Leaf Blower into an outlet using the extension cord.
While holding the beach ball up, activate the leaf blower
The ball will then be suspended in mid air.
Scientific Principles
Bernoulli studied how the movement of air and fluid was affected by pressure. When the speed of moving air increases the pressure decreases proportionally. Because of the differences between the most quickly moving air, and the slowest, the beach ball is pushed to the center. Since the flow of the air is already enough to compensate the beach ball’s weight, the beach ball is suspended in the air.
Action Video
We will be investigating this effect on various different situations.
Levitating Paper Experiment
In this experiment we will witness the same effect many airplanes use to fly.
Why is one end of the paper lifted by blowing on the elevated other?
How are planes able to use this effect?
In this experiment, because the air above the paper is moving at a high speed, the air pressure is greater below the paper, and the paper rises up to where there is less pressure. Planes utilize this effect by the shape of the wing. The wing causes the air above to move a greater distance to wrap around the wing as the plane moves. However the air above the plane must reach the same position as the air below at the same time. Therefore as the air above moves at a greater speed, the pressure proportionally decreases and results in an upward lift increasing the forces against gravity as a plane flies.
Gravity Defying Plastic Ball
Why does the ball not fall back into my hand?
When blowing into the tube the air comes out in all directions around the ball. As soon as the air traverses the ball the magnitude of its speed decreases tremendously. Therefore the air surrounding the ball has much less pressure than the air below the ball. This causes the ball to stay in its current position and not fall back into my hand.
Bernoulli Principle Prop
elled Ball LauncherWhy are the balls compelled to fire directly out of the tube when there is no direct action on the balls themselves?
As the air blows directly on the exit of the tube, the air inside the tube is compelled to move towards the top where there is less pressure. This creates a suction effect causing the balls near the other end to shoot out at high velocities.
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