Inside: it’s never too early to start teaching physics to kids. Grab a bucket of sand and some LEGO bricks for a quick demonstration of the Brazil Nut Effect.
Have you ever looked at a bowl of mixed nuts and wondered why all the large nuts are on top? It seems to be counterintuitive. Shouldn’t all the big, heavy pieces end up at the bottom? What’s more, it’s totally inconvenient, if like me you prefer other nuts. (My favorites are hazelnuts. What about you?)
Why did it always happen?
The question was killing me!
Finally, in a moment of despair I googled “why Brazil nuts are always on top.”
Turns out it’s a scientific phenomenon, my friends, called Brazil Nut Effect! Scientists, to be precise, physicists, in white coats are studying it in a lab!
Brazil Nut Effect (it’s official name isgranular convection) refer to size-separation of granular material in response to jostling and stirring. It means larger objects end up on a surface of a granula material containing a mixture of different sized objects.
Wait a minute!
Does it mean if you throw a bunch of LEGO pieces in a bucket of sand, they will all pop up?
We had to try!
We decided to try our experiment on the beach, but you can try it anywhere (your backyard, park sandbox, etc). All you need is a bucket of sand and a handful of LEGO (or LEGO DUPLO) blocks and characters.
Brazil Nut Effect with LEGO and sand
What you need
LEGO (or LEGO DUPLO) blocks and characters
What to do
Fill your bucket halfway with sand and add LEGO pieces.
Pile up more sand into the bucket.
Ask kids what do they think is going to happen.
Shake a bucket to and fro. The goal is to create a vertical vibration. Watch our video below.
See LEGO pieces popping up out of the sand?
We were so surprised that a simple shaking motion can uncover all our LEGO pieces we kept doing it again and again and again. With LEGO bricks of different sizes and shapes. With DUPLO blocks and characters. And in different buckets.
NOTE: Why fill the bucket halfway with sand before adding LEGO pieces? To speed up the results. You can put LEGO pieces at the bottom of the bucket and fill it all the way to the top with sand, but it will take much longer for LEGO pieces to work their way to the top and your kids might lose interest.
Kids can also hide each LEGO piece into the sand with their own hands. My 3-year old likes to push each piece into the sand manually.
What is happening
As you shake the bucket the particles from the center of the container are pushed upward. This leaves small empty spaces that are filled by small particles sliding down. But unless a big gap opens up among the small particles, the bigger pieces can not go back down. They stay on top.
There is a little nuance to Brazil nut effect that you might or might not want to mention depending on the age of your children. If there is no substantial difference between the density of bigger participles and smaller ones, the objects will stay mixed. You can experiment with this when kids are older.
Time at the beach is always about discovering and exploring. But if you are looking to sneak in an extra dose of physics then add this simple science activity to your next trip to the beach.
If you like playing and learning with LEGO, check out some other LEGO posts.