If a Ziploc® brand bag full of nuts is shaken, which pieces will end up at the top? You might guess that the bigger, heavier pieces sink to the bottom, but that’s not actually what happens! In this experiment, you will see the Brazil nut effect, where larger objects rise above smaller ones. This effect is named after Brazil nuts, which tend to end up at the top of mixed nut cans, but it can happen with all sorts of dry snacks (we’re looking at you, muesli and trail mix). In order to really see the Brazil nut effect in action, let’s experiment with something super small (like rice) and something much larger (like jumbo marbles).
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So how do the marbles work their way to the top of the bag? The shaking motion causes the marbles to move, leaving little gaps beneath them. The smaller and faster-moving rice grains move into these gaps, working their way under the marbles. With enough shaking, the larger marbles rise all the way to the top, thanks to the smaller rice grains that shift and build up beneath them. So now you know how to bring all the delicious clusters to the top of your cereal box! Want to save some of the chunky pieces for later? Just flip the box over and give it a shake to help redistribute them.
STEPS
- 1 Gather your materials.
- 2 Create a layer of marbles at the bottom of a Ziploc® brand sandwich bag
- 3 Add in 2 cups of rice. The bag will be about halfway full.
- 4 Gently cup the bag with both hands. Shake the bag back and forth maintaining your hands in a cupped position.
- 5 As you shake, watch what happens. Did the marbles rise to the top?
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6
Try this simple project with other items in your pantry and in your house. It works best when mixing items that vary a lot in size (like marbles and rice). What other materials might be good contenders to show this effect in action?
TIP
We found this trick to be particularly handy when we wanted to find all the large candy coated chocolate nuts in our trail mix bag!
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