Tuesday, August 09, 2016

Here lies a drinking bird

In our Thermodynamics unit students observe a drinking bird's motion to try and figure out how it works. I ask them a series of questions to guide them but several come to the wrong conclusion. Now I set up drinking birds with hot water, ice water, isopropyl alcohol and one without a cup on the second day. I ask students to apply their original explanation to the second day and that helps a few more of them. I tell students that a doctorate level thesis was written on this seemingly simple bird so it's ok if they need a one time to understand it. There are several common wrong answers:
- The liquid from the cup goes into the bird through the beak.
- Heat from the room expands the gas in the bottom bulb forcing the liquid up  (Close, can be seen if you hit the bottom with a hair dryer or hold it in your hand briefly. Try to avoid doing this in front of the kids to avoid this misconception.)
- The liquid inside the bottom bulb is heated by the room and expands.

The birds are occasionally handled too rough. I mounted one such poor bird and will add a little tombstone under it. I scraped the felt off part of the head so students could see how the top bulb was connected to the bottom one. I would like to take all the felt off of a functional head for students to compare as well. I had to add some hot glue inside the head (the cloudy white you see) in order to keep the broken fragments together. I hope to add a plaque:

Here lies a Drinking Bird
Devoted and tireless worker who only wanted
to help others understand fluid expansion and heat flow. 

Too much? 

1 comment:

Ray Hall said...

where are his legs?! Must have been total carnage.