Force-full Cereal

cerealDid you know that your cereal may be magnetic? Depending on the brand of cereal you enjoy in the morning, you’ll be able to see the magnetic effects right in your bowl. You don’t have to eat this experiment when you’re done, but you may if you want to (this is one of the ONLY times I’m going to allow you do eat what you experiment with!) For a variation, pull out all the different boxes of cereal in your cupboard and see which has the greatest magnetic attraction.

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42 Responses to “Force-full Cereal”
  1. tsyed says:

    Thanks a lot! Cool experiment’s you have.

  2. tsyed says:

    Try grape nut cereal it has 16.2 iron. I even lifted up the cereal with a magnet!

  3. Aurora says:

    Because of the iron inside! Did you read through the text below the video?

  4. Cathy Clifton says:

    Why do they connect together?

  5. Tracy Davis says:

    why is that?
    Judah 8

  6. Aurora says:

    Yes, you are correct that all things exert a gravitational pull (even tiny neutrinos!), although what we observe here is the result of something different. For one, there is adhesion happening between the liquid molecules and the container. This causes the liquid level to be slightly higher at the edges of the container. Secondly, the cereal is exhibiting buoyancy, which will cause the cereal piece to lift up as much as possible until it displaces its own weight of water. Due to buoyancy, an object will seek the highest point of a liquid surface, thus the cereal will want to travel to the sides. In addition to the iron in the cereal causing a magnetic reaction, this is another reason the cereal tends to clump together. When you drop a Cheerio in a bowl of liquid, it displaces a small amount of water. This forms a small hill around the Cheerio, and the buoyancy causes a neighbor Cheerio move toward this slightly higher surface. So in this one experiment we actually saw a number of different scientific principles.

  7. Lee Wells says:

    My son has been talking about the univeral law of attraction OF MATTER. There is nothing metaphysical in his radar, as he is only 12! I am not a scientist, but I understand the inverse square law and now so does my son, at least the significance of the location of the two masses in the numerator and the radius (squared) in the denominator of the ratio. We have been intentionally avoiding the term “gravitational” since that is typically thought of as specific to the earth. Perhaps that was the misunderstanding. Yes, we know that gravitational force NEAR THE EARTH is directed toward the center of the earth, but gravitational force of the sun (for everything in our solar system) is directed toward the center of the sun! Technically, we are pulling on the earth, too, but the earth is pulling on us much harder than we are pulling on the earth, so the NET force is directed toward the center of the earth. It seems that the buoyancy of the objects floating in the bowl would “cancel out” the earth’s gravitational force and allow their gravitational force toward each other to be observable. We also notice that all floating objects in the bowl (usually) end up against the bowl if left sitting long enough (unless by chance some other arrangement of equilibruim is achieved). Our explanation for this is that the bowl is also MATTER, so the floating objects are attracted to IT. We can even observe the effect of the relative masses of varous objects in the bowl. We are confused by your continual downplay of the universal law of (gravitational) attraction. We are simply looking for confirmation that this “universal attraction” of ALL MATTER TO ALL OTHER MATTER explains (at least in part–but I would argue PRIMARILY) the attraction between the cheerios (and all other obects, which now include broken bits of a toothpick) floating in the bowl.

  8. Aurora says:

    Gravitational attraction is only one-way, toward the center of the Earth. I am guessing that the attractive forces you are watching are perpendicular to this direction, so that can’t be it.

  9. Lee Wells says:

    No! I meant gravitational attraction!

  10. Aurora says:

    There are four types of forces (electromagnetic and gravitational are the ones in question here), which you can read about in the main reading section for this unit.

    The “universal law of attraction” – are you thinking about the metaphysical “law of attraction”? If so, that’s out of the scope of this project, as it would require the water bottle caps themselves to have a consciousness in order to set an intention.

  11. Lee Wells says:

    What about the universal law of attraction? Couldn’t it still be that?

  12. Aurora says:

    When you say “it still worked” you mean that they still stuck together? It can be hard to ground plastic since they don’t really conduct electricity, and they can build up a charge again quickly (like when you unroll a piece of tape from a roll, it picks up a static charge just by being unrolled).

    Thinking like a scientist, the question you may want to answer is this: “Is this effect due to magnetism or static electricity?” Since they are so small, it’s going to be hard to tell if there’s a static charge. (You would do that by bringing an electroscope near and seeing if the leaves deflect). You can bring a strong magnet close and see if that influences the caps (like a neodymium magnet) to rule out magnetism.

  13. Lee Wells says:

    We tried the water bottle lids again after grounding them and it still worked.

  14. Aurora says:

    They may have a static charge on them, which is not a magnetic north-south force, but rather a plus-minus force. This is true especially for plastic objects like water bottle caps. Try grounding them first (touch them to a metal pipe like on your kitchen sink) and then do it again. Do you get the same result?

  15. Lee Wells says:

    I know that the universal law of attraction is what makes this work. But in some of your responses to other questions asking how it works, you mentioned the iron in the cereal. We tried this experiment with other things that don’t have iron in them, (water bottle lids and toothpicks), and it still worked. What does iron have to do with it? Does it make it go faster, maybe?

  16. Lee Wells says:

    Rice Chex works too! This was fun!

  17. Aurora says:

    Gosh – you’re right! Total typo on my part! πŸ™‚

  18. Opal and Flora Radding says:

    We successfully did this experiment but are wondering: why did we need magnets? We messed around with them, but did not see any part of the experiment that called for their use?
    Flora and Opal, mom and ten year old

  19. Aurora says:

    Other irons? Do you mean other cereals? If so, then yes… get one that is “fortified with iron” and it’ll work.

  20. Melissa Pascale says:

    can other irons work with this?

  21. adamant says:

    We used Os and water in a ceramic bowl. They moved a little bit with we just used a spoon but when we tried a bar magnet they moved a little faster. Then we tried it with krispy rice and it worked! Pretty cool!

  22. Aurora says:

    What you see happening is really cool. We can find all kinds of interesting reasons for the attraction like magnetism, the universal law of attraction, or magic. In reality, it is surface tension and buoyancy. Buoyancy keeps the Cheerios afloat, and surface tension makes the surface of the milk act like a thin sheet, an elastic membrane. Look closely at each O and you will notice that the milk membrane creeps up the sides of each O, forming an upward slope. The slope that is created pushes down the milk around each O, creating a ring-shaped depression. When two Os approach each other, they slide into each other’s ring-shaped depressions. In fact, any cylindrical object floating in liquid will do the same thing. Think of the way that apples congregate in a wash tub how marshmallows behave in hot chocolate.

    Physicists were so interested that one day they actually took time to study the phenomenon. When they had discovered the reason, they even gave it a name, as all good scientists do. It is known in the scientific community as the Cheerios Effect. No foolin’….really.

    The phenomenon of things putting themselves together due to surface tension turns out to be surprisingly important to nanotechnology, which is engineering on the smallest scale. Nano engineers call it self-assembly. For example, microscopic spheres in liquid will come together to form a sheet with holes between the spheres. Nano engineers use these sheets – called lattices – the way painters use paper masks to spray-paint neat letters on signs, but at a scale a billion times smaller. For example, they use a lattice to deposit tiny metal dots on surfaces – an important step toward building microscopic electronic circuits.

    I hope this explanation helps. Have fun with science!

  23. Dianna White says:

    My son and I have done this experiment – one of our first – and we are confused. Why did the cereal come together is our question? I understand doing the experiment in order to figure it out but how do we know if we are right? Does the iron in the cereal have something to do with it? Is it simply that everything has gravitational pull? I feel that without answers, the experiment although fun is meaningless. Am I missing something? Thanks for your help. Dianna and Drew

  24. Aurora says:

    The liquid in the video I made used water. It would be interesting to experiment with different beverages in the cereal bowl. Let me know what you figure out!

  25. Carmenza Coleman Salgado says:

    Aurora, can this also work with juice, coffee,tea,soda, alcoholic beverages, etc. all also with cereal? I tried milk and “o”s and it worked very well. Krishnaya Coleman Salgado, age 8 1/2

  26. Aurora says:

    It’s totally possible that you have residual magnetism in the spoon, so yes, that might be what’s going on. If it’s a plastic spoon, then it would be a static charge, not magnetic.

  27. Jill Sisson says:

    O’s are all gone now, so we can’t play around with them anymore!
    We didn’t try putting a magnet by them, but one of the boys discovered that they moved toward the spoon (both convex or concave side). Is that for the same reason you explained they only seem attracted to the sides of bowl?

  28. Aurora says:

    You’re right – there are opposite forces on the “o”, but are they electrical charges (plus and minus) or magnetic poles (north and south)?

  29. Susan Josch says:

    I tried this experiment with “O”s and when one o got close to a group it moved in the opposite direction until it rotated itself around. There is a positive and negative charge on the O’s. Robert,age 11

  30. Aurora says:

    Hi Kelly! Great thinking adding the soap to the water – I hadn’t thought of that. πŸ™‚ You actually have a number of things going on, some of which you already figured out. When you added soap to the water, you lowered the surface tension of the milk/water (soap makes water more elastic and stretchy), so the cereal was able to move about more freely. The iron in the cereal is small, so unless you have a large, strong magnet, you’re not going to see much movement. The iron in the cereal also act like tiny magnets because they carry with them a teensy bit of residual magnetism, so they are either attracted or repulsed by each other, making them seem to ‘stick’ to the sides of the bowl because they are so free to move around that they eventually buddy up with the sides of the cereal O that they like best (north-south). Occasionally you’ll get a free-floater in the middle, but because the bowl is comparatively small and the milk is warming to room temperature (and thus has weak convection currents inside), the free floaters eventually hook up with the rest of the O’s. Does that help?

  31. Kelly Elmore says:

    Why can’t we move the cereal with a magnet? We were wondering if it might be surface tension that made them move together, so we added soap to the water. It seemed to make the attraction less. That made us think surface tension had something to do with it. Can you help explain more?

  32. Debra Thomson says:

    This is one of the science experiments you can eat! πŸ™‚
    Holly Thomson 11

  33. Aurora says:

    You’re right – a plastic bowl won’t have much to do with it. Let me give you a hint: have you tried the Magnet Boat experiment? The cereal has tiny bits of iron in it that carry a tiny bit of residual magnetism with it. Check out the magnet boats and see what you come up with… and post it here! πŸ™‚ (I promise to answer your question… but first I want to see what you can think up… you’ll never get this opportunity again once I answer your excellent question.)

  34. Amy Patterson says:

    I don’t know, because we tried it in a plastic bowl, so its not the bowl thats magnetic…

  35. Aurora says:

    Hmmm… great observation and question! What do YOU think? πŸ™‚

  36. Amy Patterson says:

    We were wondering why it always groups in the sides, never in the middle?

  37. Aurora says:

    No problem about ‘bugging’ us… we love getting all the feedback we can to make sure our site is top-notch.

    As it turns out, we partially uploaded the new stuff for next week’s Unit 3, which is why you are getting the error… so you are a step ahead of the game! We just set up the structure on the back end today and are uploading all the videos and content over the weekend. (Well, the computers are, anyway. I am off to figure out new science stuff in my lab.)

    Thanks for keeping a careful watch!

  38. Debra Thomson says:

    Sorry, me again. In Unit 3:Matter, in Lesson 2: Solids, I found another loose end. When I click on read in ‘and afterward either read more about it or…’, it takes me to ‘Error 402, the page no longer exists’.

    Just wanted to let you know! Sorry for bugging you again…:(

  39. Debra Thomson says:

    Wow! That is so interesting! We actually did something before where we used a magnet to pull the iron out of our cereal. πŸ™‚
    Do you mean that soap is magnetic, too? Hmmm, cool!

  40. Karen Frederick says:

    This was great! I’ll never look at Cheerios the same again!

  41. Aurora says:

    Take a look on the side of the cereal box… did they include IRON as an additive in the cereal? Now you know what they add when they say something like: “Now with 13 essential vitamins and Minerals…”

    (Hint – O’s aren’t the only cereal this works with)

  42. Veronica Cable says:

    Why are the O shapped cearal magnetic?!
    Seva Cable, 9 yrs. old.

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