1. Crushing Can:
* Materials: Empty aluminum can, water, heat source (stovetop or burner), tongs, bowl of cold water.
* Procedure:
* Fill the can with a small amount of water (about 1/4 cup).
* Heat the can on the stove until the water boils and steam escapes.
* Carefully use tongs to quickly invert the can into a bowl of cold water.
* The can will immediately collapse inward.
* Explanation: The boiling water creates steam inside the can, pushing out most of the air. As the can cools, the steam condenses back into water, leaving a near vacuum inside. The pressure of the air outside the can is much greater, and it crushes the can.
2. Straw in a Glass of Water:
* Materials: Glass of water, drinking straw.
* Procedure:
* Place the straw in the glass of water, and cover the top of the straw with your finger.
* Lift the straw out of the water while keeping your finger on top.
* Observe that the water stays in the straw.
* Explanation: The air pressure outside the straw is greater than the pressure inside the straw, keeping the water trapped.
3. Balloons in a Vacuum Chamber:
* Materials: Vacuum chamber, vacuum pump, balloons.
* Procedure:
* Place a few balloons in a vacuum chamber.
* Use a vacuum pump to remove the air from the chamber.
* The balloons will expand as the air pressure outside decreases.
* Explanation: The balloons expand because the air pressure inside the balloons is greater than the decreasing pressure outside.
4. Simple Barometer:
* Materials: Tall glass jar or container, clear plastic drinking straw, water, measuring tape.
* Procedure:
* Fill the jar almost completely with water.
* Carefully place the straw into the jar, making sure the end of the straw is submerged in the water.
* Use the measuring tape to mark the water level in the straw.
* Observe the water level in the straw over time. It will fluctuate slightly due to changes in air pressure.
* Explanation: The pressure of the atmosphere pushes down on the water in the jar. This pressure is transmitted through the water and up the straw. Changes in air pressure cause the water level in the straw to rise or fall.
These simple experiments demonstrate that air exerts pressure, and that this pressure can affect objects in various ways.
