Sunday Science - Puffers

We continued our investigation of forces this week by focusing on the air/water pressure.  We made ping pong puffers.  With just a straw and a bottle cap, we demonstrated how powerful air pressure can be.

To set the stage we looked back and remembered our balloon experiment, where the air powered our balloon ship.

Then we put together our puffers.  The kids first blew through them with their hands on top to feel the air.  then we placed the ping pong ball on top.  You need to blow really hard with a constant stream to get the ball to float on top of the column of air without touching anything.  The kids could not maintain the stream enough for floating but had fun making the ball spin. I floated the ball for them so they could at least see it. Here is what it looks like when it works. (image borrowed from someone else's experiment)

We also looked at the same principle using water.  We taped a ping pong ball to a string.  Then place the ball near a running faucet but not in the water.  The column of water will actually pull the ball into the stream.  Each kid got a chance to do this and feel the pressure as the water tugs on the ball pulling it closer.  This part was much cooler than anticipated as the lightbulbs went off in many little heads.