By Debby Venable
Oklahoma STEM Ambassador
I can remember as a child going to the grocery store and wandering down the cereal aisle with wide eyes searching each and every box, not for nutritional information, but for the box that held the one and only greatest prize that could be taken home with just the purchase of the box. Toy stores had nothing on that cereal aisle. I think the best part of the adventure was trying to guess just what prize was buried beneath all that cereal. It was like searching for buried treasure, and I was the pirate that was waiting to uncover all that “booty”. It was really hard to not try to stick your hand and arm all the way down the side of that box and snatch that buried treasure that awaited me. What am I saying, I did try to get to the bottom of that box with my hand and skip the eating bowl after bowl of that cereal. After all, some of the boxes that held the best prizes had the worst tasting cereal, ugh!!! I would eventually have to give up and eat that cereal just to uncover my pirate treasure, because my mom was the best detective ever. She could spot a bent box a mile away, and I would not dare pour cereal out and put it back into the box. Wow! That was the ultimate sin. “You buy it, you eat it. Prize or no prize. I did not think about science or anything as technical as that. I just knew that the prize was at the bottom of the box and nothing I did was going to bring it to the top.
Now that I am “science savvy”, I know that the cereal particles were lighter that the prize, and therefore lies the dilemma. How do you get something that is heavier than the other rise to the top? So, I figured that this can be duplicated with a test tube, salt, and a marble. What you are asking, does this have to do with my cereal and my prize? Just bear with me and use your imagination. It is all about the principle of the weight of different particles.
Try my experiment and see what happens. Any predictions? Care to make a guess? Here are the directions to this simple, yet effective, demonstration of particle weight and friction.
After you perform the experiment, you may be wondering what does this have to do with finding the toy surprise in my box of cereal. Well…..use the same technique you used with the marble experiment to make the toy surprise rise to the top to the cereal box. Hold the box vertically and shake it up and down. You may crunch up the cereal a little, but you know that the prize is the most important thing in that box! Each time that the box is jerked upwards, the toy surprise moves up through the cereal to eventually emerge from beneath the flakes, To everyone’s amazement, you’ll be able to open the box cereal and have the toy surprise just waiting on you at the top of the box. That’s physics at its best in action!!
Mom will be happy that you have put your science knowledge to work and not destroyed the box of cereal, and you will be glad that you got the surprise that lured you into that cereal aisle to begin with.
WHAT A CRACKER JACK SURPRISE!
- Plastic test tube with lid or an empty peanut butter jar with lid
- Fill the container ¾ full with salt
- Place the marble on top of the salt.
- Seal the end of the container with a cap
- The challenge is to get the marble from one end of the container to the other, through the salt. Go ahead….shake the container…twist it…spin it… anything you want to do. Don’t give up, you will find the solution.
HOW DOES IT WORK:
Hold the container vertically with the marble at or near the bottom. As you shake the container up and down, the marble will actually rise through the column of salt. Each time the container is jerked upwards, both the marble and salt move up at the same speed. Because the salt particles are lighter and smaller, they experience greater relative friction than the marble when rubbing against the other. This causes the salt particles to slow down faster. After each shake, more salt particles are packed underneath the marble, until it magically emerges from beneath the salt.