Tuesday, May 8, 2012

The Joy of Poi

Swing your poi!  Let it swing back and forth.  If you don’t disturb it you’ll notice it will finally come to rest. This is a pendulum.

A pendulum is very simple.  It’s a weight on a thread or on an arm that swings back and forth. They are used to regulate clocks so they don’t tick too fast or too slow.  Today’s experiment will help us understand pendulums a little more.

You will need:
Large metal washers
Ball of string
Protractor (Optional)

  1. Cut a piece of string to 1500mm long.
  2. Work out a way of hanging the string.  A doorway is good.
  3. Now tie your washer to the end of the string.
  4. Pull the washer back, keep the string straight.  Try and make a 15 degree angle. 
  5. Let go of the washer.
  6. Count how many times it swings back and forth within 60 seconds.
Alan in his glam shed :)
Repeat the experiment but increase the angle to 40 degrees.  What’s the difference in the result?

Now shorten the rope to 1000mm and swing it from 15 degrees. How does this compare to our first result?

Do it again but shorten it down to 500mm. What happens?

Other things to try:
Collect your data on a chart.
Do each swing five times and work out an average. 
Look at your data.  Are there any patterns?
Change the weight by adding more washers.  What happens then?

Don’t forget we have a free Science Week PD Session in Auckland tomorrow.  If you are a teacher you are very welcome to join us.  Fill in the registration form so we know how many red sausages to buy.

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