Wednesday, April 1, 2015

Emptying a Bottle Experiment

It may be April Fool's Day, but this science experiment is no joke!  Have you ever tried to empty a bottle of liquid by holding the bottle directly upset down?  Give it a try and observe what happens.  Although the liquid empties relatively quickly, it doesn't empty as quick as it could.  For water to leave the bottle, air must enter.  If the bottle is held upside down, air bubbles must work up through the liquid to get into the bottle.  This slows the liquid pouring out.  By tilting the bottle slightly, there's always a gap between the liquid and the air, allowing the air to more easily enter.  This experiment tries something a bit different.  A bottle will still be held directly vertically, but the bottle will be rotated in a circle instead of remaining stationary.

Which bottle empties first?  The motionless bottle or the bottle being moved in a circle?  I tested this out with my girls the other day and here is our video.

video

Yes, that is a bottle of flavored Smirnoff Ice.  LOL!  

It's a bit tough to see from the video, but the circling bottle empties slightly before the stationary bottle.  Why?  By moving the bottle in a circle, the liquid inside isn't pouring straight out the bottom of the bottle.  It twirls around the edges, leaving a gap in the middle for air to more easily enter.  In this way, it's similar to tipping the bottle slightly when pouring.  

Try it out yourself.  You may find using two liter bottles to be more effective.  I'm not sure, but it's something we may test out in the future.  With more liquid initially in the bottle, there may be a greater time difference at the end.  

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