Buoyancy Experiment

The more I homeschool, the more I realize I DON’T know everything.


When I first saw this Buoyancy Experiment, I thought to myself…that will NEVER work!

I had my doubts a chip bag could float with the weight of 100 pennies.

Yes, I was sure I knew more than the scientist who put this together.

So, who was right?

Let’s try the Chip Ship Experiment from Potato Chip Science by Allen Kurzweil {and find out if Allen knows a little more about buoyancy than me}.

Sink or Float?

Or as I like to call it…

buoyancy experiement materials It will NEVER float!


  • 100 pennies
  • chip bag
  • bucket of water
  • lid that fits into chip bag and will keep it open

Note:  The instructions say you may use a single serving chip bag and a smaller lid, but this is what I found at my house. I was forced to eat the last few pita chips.

buoyancy experiment pennies in bag Instructions

1. Load the pennies into the empty chip bag “boat” making sure they are evenly distributed.

buoyancy experiment sinks 2. Gently lower your penny-laden “boat” into a bucket with at least 5 inches of water and watch what happens.

buoyancy experiment lid in a bag 3. If your “boat” sank, then take it out of the water and add the lid on top of the pennies so that it keeps the bag in an open position.

buoyancy experiment floats 4. Gently set the “boat” on the water again.

Yep, the “boat” floats despite the 100 penny cargo!

Why does this happen? Positioning a lid on top of the pennies broadens the hull of your chip ship, which increases the volume inside the vessel and the amount of water displaced outside. The pennies at the bottom of the chip ship also serve as ballast–weight that improves stability. This is how a cargo ship filled with a very heavy load can stay afloat.

Oh, and I might mention that I was wrong…shhhhh!

You can find a free download with printed instructions for this experiment from Workman Publishing.

4 days later teeth whitening

About Holly

Kids Activities Blog is Holly's blogging home.

She is the mom of three boys ages 7, 10 and 12 who partially homeschools. She believes that you shouldn't have to buy stuff to have fun when there is a kitchen junk drawer full of possibilities.

She can also be found at Business 2 Blogger, on Twitter as @QuirkyMommaSite or @Texasholly, but her favorite place to hang out is on Google +.