Theory & Background
Did you know that air around us has incredible properties? As per the principles of air pressure, a moving stream exerts less pressure than the air surrounding the moving stream and a quick air stream has a lower pressure than a slow moving one.
Required Materials
- Plastic straw
- Table-tennis ball
Estimated Time
Less than five minutes
Step-By-Step Procedure
From one end of a plastic straw cut a 10 cm piece
Put one end of the straw in your mouth and tip back your head
Hold a table-tennis ball a few inches above the other end of the straw
Blow as air hard as you can through the straw while releasing the ball simultaneously
Experiment Tips
- The harder you blow, the higher the ball will float above the straw.
Observation
As long as you blow air through the straw, the ball remains suspended in mid-air.
Result & Conclusion
The reason why the ball remains suspended in air is because it is actually ‘imprisoned’ by the column of upward rushing air. The air that is in rapid motion has a lower pressure as compared to its surroundings and owing to this, as soon as the ball moves even slightly to one side, the greater pressure outside the air stream forces it back into the fast moving air stream again.