The Power of Steam

I sometimes wonder if people on a train really understand what is getting them from one place to another. I wonder if they understand that the power behind this train is one of the most amazing forces we have harnessed and that in harnessing that power we have cause a technology revolution. Steam is such a simple concept yet so powerful.

I remember when I was little sitting in the kitchen with Mum making tea and playing with my brand new pinwheel that Father had brought home from one of his many trips to Dublin. It was pretty when it spun. I remember Father coming in and telling me he wanted to show me a secret. He had me stand up next to the stove and teapot with my pinwheel and he put the edge of the pinwheel into the stream of steam. The pinwheel began to spin very fast! Father explained that instead of blowing on the pinwheel to make it turn the steam was making it turn. He explained that the pinwheel was now steam powered and being able to control the hot steam was all that was different between that pinwheel and making the steam train move.

Want to make a steam powered can?

You will need to gather:

  • A can of soda
  • A nail
  • A bucket of water
  • A one yard length of string
  • A lighter or matches
  • A gas burner or candle

Be careful! Steam is very hot and you will need an adult to help you for this experiment.

What should you do?

  • Holding the can over the sink use the nail to make a small hole in the long side of the can. Make a similar hole in the opposite side of the can.
  • Drain all of the soft drink from the can.
  • Push the nail into one of the holes. Turn the nail to the right until it lies flat against the can. In this way, the metal of the can is twisted to create a hole facing to the right. Repeat this same action on the opposite hole, still turning the nail to the right.
  • Tie the string to the hole on the tab at the top of the can to allow the can to hang vertically when suspended by the string.
  • Hold the can on its side with one of the holes facing up and lower the can into the bucket of water. Push the can into the water and fill the can with water to a bit under the holes you created.
  • Remove the can from the bucket.
  • Hold the loose end of the string and hang the can over the candle. Use the lighter or matches to light the gas burner or candle and wait until the water boils and the can spins. This will take some time because water takes a while to boil.
  • Once you see the can spinning, turn off the gas burner or blow out the candle and place the can in the bucket of water or in a sink to allow it to cool.

What’s really happening?

The flame heats the water inside the can until eventually the water starts to boil. When water boils it changes from liquid water into steam. The steam inside the can builds up pressure and starts to push out through the holes in the side of the can. When the steam is moving fast enough out of the holes, it causes the can to move in the opposite direction and the can starts to spin.

Water exists in three states, solid (ice), liquid (water) and gas (steam). When enough heat is added to or removed from water it will change between these states. In this activity, heat is added to liquid water causing it to boil and evaporate to form gaseous water, commonly known as steam.

Steam takes up a lot more space, called volume, than liquid water because water molecules in steam are more widely dispersed. There is a lot of empty space between the water molecules in steam and those molecules contain more energy and move more rapidly than the molecules in liquid water.

As the water in the can turned into steam, the steam filled the can. The pressure inside the can increased as more and more steam was produced. The holes in the can were the only spaces through which the steam could escape. The holes were bent at an angle to direct the flow of the steam. According to Newton’s Third Law of Motion, every action has an equal and opposite reaction. When the steam pushed out of the can in one direction the can was pushed in the opposite direction, making the can spin.

The pressure created when water turns into steam can be harnessed to make something move. In the Industrial Revolution, early locomotives, steam-boats and factories were powered by steam. The ‘choo-choo’ sound associated with trains is made by steam-powered locomotives. When the exhaust valve of a steam-powered locomotive opened, it released the train’s steam exhaust under great pressure, making a ‘choo!’ sound.

Posted By Astrid

2 Responses to “The Power of Steam”

  1. David Mackie says:

    This is Awesome … I want to extend it a little.

    If I can put an electric motor on the can with a frame to support and stablise everything then I’d have a powerstation since a generator is essentially a motor backward and how we made AC power from DC in old submarines (use a DC Motor to drive an AC Generator) before static inverters.

    Just add Water and Tea Light Candles wonder what I can run from it??

    So where to find a Motor I might have a broken flying model plane kicking about some where ;)

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