Calm amidst the storms.

10 minutes


  • Carefully review the general safety advice on the back of the box cover before starting the experiment.
  • Read the "Working with Batteries" section of the safety guidelines carefully before proceeding. Always disconnect the setup after finishing the experiment.
  • Disassemble the setup after the experiment.

Step-by-step instructions

The perforated plug—the flow straightener—changes the direction of the air flow coming from the propeller. Protect the propeller with a restrainer.


Turn on the propeller and watch the ball levitate!


Do you want the ball to hover even higher?


Which ball will win and be able to stay in the stream?



  • Dispose of solid waste together with household garbage.
  • Dispose of used batteries in accordance with local regulations.

Scientific description

As they collide with solid objects, the moving parts  of the air change their direction . Therefore, as it passes through the flow straightener , the vortex  transitions into a straight upward flow .The flow  consists of air parts  accelerated by the propeller . These parts slow down when they collide with the still air around them. The farther the flow  travels from the propeller, the more collisions it experiences, and the more it weakens.

The straightened flow  pushes the ball  upwards, while gravity pulls the ball down. As a result, the ball  hovers at the height where the flow force is strong enough to hold it. The ball cannot hover at other heights. When colliding with the ball, parts of the airflow  go around it and support it in the center. Two identical balls  cannot stay in the stream because they are competing for one spot. As a result, one of the balls  will take this place, and the second  will fall out of the stream.

When the pipe is installed, the ball can hover at a greater height. The flow  is not weakened as much in the pipe, as this limits its contact with the surrounding air.