Monday, March 1, 2010

Air Pressure: Crush a Soda Can

Place a small amount of water in an empty soda can. Place the can on a hot plate and heat until the water boils. While waiting, prepare a large container of cool water. Once the water has begun to boil, use tongs to pick up the can and quickly turn it upside down and place it in the water bath. The air in the can heats up, the air molecules start moving faster and some find their way out of the can, creating an area of low pressure. Turning the can upside down into the water creates a seal in which no air molecules are able to re-enter the can. The pressure outside of the can is greater, and the can is crushed.

To see a “real life” example of this phenomena, check out what happened to this train car when it was washed with hot water and sealed before it was cool.

1 comment:

  1. Dear Karen,

    I am requesting permission to reproduce the photo of the crushed soda can from your website. I would like to use this figure in a textbook I am preparing for publication later this year by Taylor and Francis. The book is called Energy and Society, and will be the second edition of this book. I would use this figure in the chapter on the steam engine. Of course I will be pleased to acknowledge the source in the book.

    If permission is granted to use this photo, do you have a high resolution photo that you can email to me?

    Thank you.

    Dr. Harold H. Schobert
    Professor Emeritus of Fuel Science
    Penn State University