Read Online Everything Kids' Magical Science Experiments Book by Tim Robinson - Free Book Online Page A
Authors: Tim Robinson
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also can be very nutritious. But chances are you didn't know it also can serve as a magical science experiment. Because of a relationship discovered by Daniel Bernoulli, air has the ability not only to lift up a piece of your favorite cereal, but keep it floating off the table as long as you can provide the air.
Question: Does cereal float?
Materials
Spherical pieces of your favorite cereal
Drinking straw that bends near the top
Procedure
Bend the upper part of the straw so it makes an L-shape.
Place your mouth at the long end of the straw with the bent end pointing up into the air.
While you blow through the straw, place one piece of cereal just above the far end, where the air is exiting the straw.
Try to balance the piece of cereal above your straw while you blow through it. With practice you should be able to control the height at which the cereal floats above the straw.
The Science Behind the Magic
Daniel Bernoulli discovered that in a stream of moving air, the pressure is lower than in the air outside the stream that is not moving. While the piece of cereal is in the stream of air, it stays in a position of lower air pressure. As it drifts toward the edge of the moving air stream, it hits the air with higher pressure and is pushed back into the stream. As long as the air stream remains, the cereal will stay âstuckâ in the stream and will float.
BERNOULLI PRINCIPLE: When a substance, including air, speeds up, the pressure decreases.
Follow-Up
You can explore this idea on a larger scale by setting a hair dryer on a table so that it points upward. Turn it on and place a Ping Pong ball in the air stream above the hair dryer. It should float. The Bernoulli Principle doesn't just make small objects fly, however. It is one factor that helps airplanes fly. If you research the shape of an airplane's wings, you'll see that they are designed so that air travels faster over the top of the wings than below. This creates an area of lower pressure above the wing, which helps the airplane stay in the air. Can you find other places this principle shows up? It might surprise you to see just how common it is.
The Uninflating Balloon
KIDS' LAB LESSONS
Experiment Overview
This experiment explores the fact that air takes up space. You may not be able to see it, but it's there and this experiment will demonstrate that. The goal will be to blow up a balloon inside a plastic bottle. But in the first version of this experiment, you will first attempt to inflate the balloon without placing anything else inside the bottle. You will then add a straw to see if it has any effect on your ability to blow up the balloon. In the second version, the bottle will first be untouched and then will have a small hole placed in it. Your task will be to determine whether that hole has any effect on your ability to inflate the balloon.
Science Concept
Air takes up space. You actually demonstrate this every time you take a breath. As you breathe in, your lungs expand to hold the air. When you breathe out that air, your chest and lungs deflate a little bit. In this case, you are dealing with air that already resides inside the bottle. When you try to put air into the balloon, it has to displace the air already in the bottle. With no exit path availableâthis happens in the first test when nothing is added to the bottle, and in the second when no hole is present in the bottleâthe existing air stays right where it is and it becomes impossible for the balloon to inflate. However, by adding the straw, the air now has a path to travel and it can escape. This makes room for the new air you are breathing into the balloon and it easily inflates. With a hole in the bottom of the bottle, the air inside the bottle just escapes out the hole and this is what allows the balloon to inflate.
Materials
2 (20-ounce or 1-liter) plastic bottles
Drinking straw
Thumbtack
Medium balloon
Procedures
Part I
Place the balloon inside the bottle with its mouth
Question: Does cereal float?
Materials
Spherical pieces of your favorite cereal
Drinking straw that bends near the top
Procedure
Bend the upper part of the straw so it makes an L-shape.
Place your mouth at the long end of the straw with the bent end pointing up into the air.
While you blow through the straw, place one piece of cereal just above the far end, where the air is exiting the straw.
Try to balance the piece of cereal above your straw while you blow through it. With practice you should be able to control the height at which the cereal floats above the straw.
The Science Behind the Magic
Daniel Bernoulli discovered that in a stream of moving air, the pressure is lower than in the air outside the stream that is not moving. While the piece of cereal is in the stream of air, it stays in a position of lower air pressure. As it drifts toward the edge of the moving air stream, it hits the air with higher pressure and is pushed back into the stream. As long as the air stream remains, the cereal will stay âstuckâ in the stream and will float.
BERNOULLI PRINCIPLE: When a substance, including air, speeds up, the pressure decreases.
Follow-Up
You can explore this idea on a larger scale by setting a hair dryer on a table so that it points upward. Turn it on and place a Ping Pong ball in the air stream above the hair dryer. It should float. The Bernoulli Principle doesn't just make small objects fly, however. It is one factor that helps airplanes fly. If you research the shape of an airplane's wings, you'll see that they are designed so that air travels faster over the top of the wings than below. This creates an area of lower pressure above the wing, which helps the airplane stay in the air. Can you find other places this principle shows up? It might surprise you to see just how common it is.
The Uninflating Balloon
KIDS' LAB LESSONS
Experiment Overview
This experiment explores the fact that air takes up space. You may not be able to see it, but it's there and this experiment will demonstrate that. The goal will be to blow up a balloon inside a plastic bottle. But in the first version of this experiment, you will first attempt to inflate the balloon without placing anything else inside the bottle. You will then add a straw to see if it has any effect on your ability to blow up the balloon. In the second version, the bottle will first be untouched and then will have a small hole placed in it. Your task will be to determine whether that hole has any effect on your ability to inflate the balloon.
Science Concept
Air takes up space. You actually demonstrate this every time you take a breath. As you breathe in, your lungs expand to hold the air. When you breathe out that air, your chest and lungs deflate a little bit. In this case, you are dealing with air that already resides inside the bottle. When you try to put air into the balloon, it has to displace the air already in the bottle. With no exit path availableâthis happens in the first test when nothing is added to the bottle, and in the second when no hole is present in the bottleâthe existing air stays right where it is and it becomes impossible for the balloon to inflate. However, by adding the straw, the air now has a path to travel and it can escape. This makes room for the new air you are breathing into the balloon and it easily inflates. With a hole in the bottom of the bottle, the air inside the bottle just escapes out the hole and this is what allows the balloon to inflate.
Materials
2 (20-ounce or 1-liter) plastic bottles
Drinking straw
Thumbtack
Medium balloon
Procedures
Part I
Place the balloon inside the bottle with its mouth
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