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Monday, November 25, 2013

Floating balls

We were looking at floating balls today.
We can get a ping pong ball to float on the air stream from a hair dryer.
The air pushes the ball up and gravity keeps pulling it back down into the air stream.
In fact we can get two balls to float at the same time.
Can you guess what will happen when we try this out with a bouncy ball?
That's right!  The bouncy ball is not hollow in the middle and is not filled with air so it doesn't float on the stream of air, it just stays where it is when the heat is turned on.
Next we floated a ball and then we tried putting a cardboard tube over the floating ball.  
Look at what happens...the air is more concentrated and so moves faster as it goes through the tube.
This means that the force of air is stronger and the ball jumps up even higher than it did before.

We tried different combinations of bouncy ball, floating ball and floating ball and each time we had to guess how many balls would come out of the tube once the heat was turned on.  
We got good at guessing by the end of the experiment.
We think we should try these at home too.

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