2C20.30-Floating Ball

2c2030floating_ball

Video: Watch this demo

Instructor’s video

Description: Using a stream of air, you can make a ball “float” inside the stream.
A variation of this is to attach a funnel to the hose. Put the ping pong ball near the inside of the funnel and it
will get sucked in, even though the air is moving out of the funnel.

Equipment:

  • Tube with funnel
  • Ping pong ball

Setup Procedure:

  1. Make sure the funnel is attached to the hose with a hose clamp.
  2. Attach the other end of the hose to the air valve in the classroom. Do not attach to the gas valve.
  3. Include the ping pong ball so it does not roll away.

Demonstration Procedure:

  1. Turn on the air pump to about half pressure (too much and the hose will pop off or break).
  2. First you can position the ball inside the stream and have it float vertically.
  3. Slowly turn the hose on its side so that the ball starts to float to the side. This happens because the ball is on the bottom of a current of air. The air is moving faster then the air on the bottom, so the pressure is less on the top. This requires a steady hand.
  4. If you place the ping pong ball inside the funnel, it will stay inside even if you tilt it upside down.
  5. Show students that it’s still blowing air out, by blowing something away.
  6. This happens because the air from the funnel is faster then the air directly behind the ball. The faster air means less pressure, so the ball stays inside the funnel (even when upside down).
  7. When finished, turn off the air valve.

32-D4

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