This demonstration uses a cork suspended in water inside a jar to show how acceleration affects fluids and objects. Instead of moving opposite to acceleration as many students expect, the cork moves in the same direction as acceleration because of pressure differences in the water.

1. Use hot glue to attach one end of a string to a cork and the other end to the inside of the jar’s lid. The cork should hang about 2/3 of the way up the jar when the string is taut.
2. Fill the jar completely with water, add the cork and string assembly, and screw on the lid tightly.
3. Place the jar upright on a table.
4. Ask students to predict what will happen to the cork if the jar is accelerated to the left.
5. Move the jar quickly to the left and observe that the cork moves left, not right.
6. Try moving the jar in a circular path. The cork will move inward, showing centripetal acceleration.

Simple Accelerometer and Circular Motion - Alom Shaha:

Accelerometer - sciencefix:

📄 A Simple Accelerometer Made of a Glass Jar and a Cork - stoppi71: https://www.instructables.com/A-Simple-Accelerometer-Made-of-a-Glass-Jar-and-a-C/

• Try using different fluids (e.g., oil, syrup) to see how viscosity affects the cork’s motion.
• Replace the cork with other floating objects of different densities.
• Use a transparent plastic bottle instead of a glass jar for safer handling with younger students.

• Handle the glass jar carefully to avoid breakage; a plastic container is safer for children.
• Ensure the lid is tightly sealed to prevent spills.
• Keep hot glue away from children when assembling the apparatus.

• Why does the cork move in the same direction as the acceleration rather than the opposite direction? (Because the water shifts due to inertia, creating higher pressure on the side opposite acceleration, which pushes the cork forward.)
• What role does water pressure play in the cork’s motion? (It transmits the effects of acceleration to the cork.)
• How does this experiment relate to accelerometers used in technology such as smartphones or cars? (Both detect acceleration by measuring how a mass responds to changes in motion.)
• What happens if the jar is moved in a circle? (The cork moves inward, showing the direction of centripetal acceleration.)