Next time you watch a drag race, notice the wheels. Are they solid metal discs, or do they have holes drilled through the rims? I came up with this somewhat silly, but incredibly powerful quick science demonstration to show my 2nd year university students how one set of rims could really make a difference on the racetrack (with all other things being equal).
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I doubt there is anything wrong with the soup. It just has to do with the “thickness” (called viscosity) of the soup. If they both roll at the same time, that means the viscosity of the soup is similar in both cans. I’d be interested to see a picture of both cans so I can see exactly what kinds of soup were used. You can email the picture to [email protected].
if both go at the same is there something wrong with the soup
COOL I WOULD HAVE THOUGHT THE CLAM WOULD WIN THOUGH.
Here is a good substitute for anyone who is having trouble finding the right soups…We froze a full Gatorade bottle and compared that to an unfrozen Gatorade. This works the same way as the frozen ice will rotate with the container however the liquid Gatorade does not. This was a great way to demonstrate inertia, and had my kids scratching their heads as to why the liquid Gatorade always won the race.
Yes, but any soup will work if it’s thick enough to be a solid, even refried beans will work.
did you use condensed clam chowder?
Not as long as they are the same size 🙂
One question: Does it matter the size of the can?
Not a problem at all… the ice stays because it’s surrounded by a fluid and not rigidly locked into place like solid object would be. Ice has more inertia (resistance to motion) than the water around it, so the water moves more easily than the ice. Great question!
Hi Aurora!
What you said about the chicken broth staying in place while the can moves got me thinking…. when you get a glass of ice water and you move the cup clockwise and counter-clockwise, the ice stays in the same place and position most of the time. Why does this happen? Sorry if it’s a little off-subject.
Arteah Rosario
Good question! I would do an experiment to find out… and then let me know what you figure out! 🙂
If the incline were longer, would the clam chowder catch up to the chicken soup since it takes longer to accelerate, but accelerates to an overall faster speed since it has more inertia?
Yes there is, but it’s in the HS level of the program where we show you how to find the friction coefficient by taking the inverse tangent of the incline angle. You don’t need any fancy equipment – just a protractor to measure the angle, a ruler to measure distance, and a stopwatch to time how long it takes each can to roll down the ramp at different incline angles. You can take data and record your observations for different incline angles without doing any fancy math.
Our question is this:
Does the difference in the incline (6 inches vs. 12 inches, for example) affect the ratio between the acceleration of the Clam vs. the acceleration of the Chicken? We were not able to figure this out without fancy timing equipment. There must be a way to figure it out mathematically, though.
You need to be logged in in order to see the video – it’s right below the fourth paragraph.
Is there supposed to be a video for Chicken and the Clam? The experiment descriptions says to “Take a guess, then watch the video, do the activity, then read the explanation at the bottom (in that order) to get the most out of this experiment”, but there is no video.
Exactly! The raw egg is similar to the can of broth, and the cooked egg is similar to the can of chowder. However, unlike the chowder which initially rolls more slowly, when spun, the hard boiled egg rotates more quickly than the sloshy raw egg. The raw egg begins its spin slowly, and then speeds up. Because the kids were familiar with the tendency of the solid egg to spin faster, they incorrectly hypothesized that the clam chowder would roll faster. I was unable to explain to them why the spinning raw egg would be slower, but the rolling can of broth would be faster.
A raw egg is more sloshy because it’s mostly a liquid inside, like the broth. The cooked egg is like the clam chowder in that it is a solid all the way through. Does that help get you started? It doesn’t have anything to do with legs… you have to think about the state of matter the substance is in, and how much inertia it has when moving. The can of broth has the can rolling around the broth, which doesn’t roll at all, whereas the clam chowder rolls with the can since it’s a solid mass.
Note that the cylinders are going to roll a lot more straight than an egg, so maybe if you make a channel to keep the egg lined up the right way?
My kids hypothesized that, similar to a raw egg initially spinning slower than a hard boiled egg, the chicken would initially roll slower than the clam. (We also theorized that the chicken would probably go faster because it has legs and clams are notoriously slow creatures.) Please comment on hard boiled vs. raw eggs, and how they are dissimilar to the rolling cans experiment.
It’s based on how we got the equation using integral calculus. In the solid cylinder, the whole thing is moving around, but with the shell, it’s only the shell itself. The 1/12 comes from the constants that get pulled out in front when the equation gets integrated.
why is Inertia of a solid cylinder = 1/2 * (mr²) & Inertia of a cylindrical shell = 1/12 * (mr²) ? i know the shell should be less but why 1/12? Also if the hole was bigger, shell thinner, would the fraction be smaller than 1/12? Super thin is almost no Interia?
The links are working now. Thanks.
that is so cool 🙂
thanks for letting me know. I’ll have my programmer look into it.
The “Download student worksheet and exercise” link is not working, again. It seems to be all on the velocity pages. This has happened before and it worked well on your end but not on other computers.
What browser and computer or device are you using? What happens if you try a different computer?
Aurora, We cannot get our video to play. Any suggestions?
The cans are affected by the same force of gravity, yes. Gravity is experienced by an object as an acceleration, however, and will ultimately affect how quickly the objects reach their top speed. The can of the chicken soup is able to reach higher speeds not because of a difference in gravity, but because there is less resistance to the can’s ability to remain at rest (inertia). The can of chowder, with its higher inertia, will have more resistance to moving. Ultimately, if the cans are both of the same mass, they will fall at the same top speed when dropped vertically. The rolling demonstration helps us see how inertia comes into the picture. You’ll find more information on this in the reading section on inertia.
Hi
My son wants to know why the cans don not move at the same speed since gravity is the force that is causing them to roll down the slope.
Thanks
Awesome! You’re nearly there: “it needs kinetic energy to overcome the friction to get started”. 🙂 Excellent job trying out these new ideas!! Keep it up!
“It needs kinetic friction to get started!” -Ryan, age 8
I don’t know if he used that phrase correctly, but he’s trying out new vocabulary in context, and simply loves science now. Thanks, Aurora.
P.S. We used a can of refried beans similar in size to the broth and they worked perfectly.
-Jodi
I used Amy’s Southwestern Black Bean Chili (thick and gloppy) instead of the chowder and Amy’s Chunky Vegetable Soup (liquid and brothy) instead of the chicken soup. They worked the same way!
-Mary Crawford (age 12)
I used coconut milk and beans, they were the same weight and the beans landed first 🙂
Yes – that’s the trick. You need to find two objects with the same mass (or weight) in order for this to work. If you don’t have a scale, you can place each can on either end of a ruler and find where the balance point is… it should be in the middle.
This experiment shows you how the rolling resistance changes depending on how the mass is arranged. In the clam, it’s a solid chunk, but with the chicken it’s made up of a sloshy liquid which doesn’t rotate around the center the way the clam chowder does. If you roll an empty can, it’s got a different mass entirely, so there are two effects going on coupled together, which makes it more difficult to observe the difference of inertia.
Yes – the gravitational constant is the same for all objects on Earth:
g = 9.81 m/s2 = 32.2. ft/s2
Do those 2 cans really weigh the same? I do not have a scale. Does it not have anything to do with their weight? A can filled with concrete would roll down slower than an empty can at first but then the can of concrete would catch up and pass the empty one, is that correct? Thanks
So if they were both dropped from an airplane, they would both accelerate at the same rate?
Great experiment. I couldn’t find clam chowder so I used cream of shrimp. It worked great. Chicken also won over chick peas and corn. When we were done we rolled a partially full bottle of juice to see the liquid not rolling but rather the container.
Hmm… that doesn’t sound right. I’ve got them playing on our systems over here. What happens if you try a different computer? I peeked into your account and you should have access.
I can not get 2 of the videos to work in this section. The first one and the last one. The pie plate ball trick is the only one we can get to play in this lesson. Trying to teach this in about 2 hours and they worked a few days ago but now say video can not be found or access is denied. Any ideas how to fix this?
The liquid needs to be very thin – no chunkiness or thick consistency… more like a can of water. My guess is that the tomato soup was too thick. Try again? 🙂
I’m trying to use soups we have in our cupboard so we used Cream of Chicken as the solid and Tomato as the liquid. We could hear that the soups were solid and liquid like they are supposed to be, but the exp. did not work as expected – the chicken always won! It started off faster and stayed ahead the whole time…I guess the soups are not as solid and liquid like as I thought. Today we’ll try refried beans and diced tomatoes – they sound very liquid like.
paula nemec
Ah, good thinking! Yes, that is why heavier cars do not win quarter-mile races, but rather mile or longer races. The heavier car will have more momentum the faster it goes, counteracting that inertia (rolling resistance).
My son wonders if the clam chowder would win if the ramp were longer. He hypothesizes that because the clam chowder is heavier it will pick up more speed the further is travels and win the race. Is that true?
It’s cool, we used Amy’s Organic Soups; Tuscan Bean & Rice, and -Fire Roasted- Southwestern Vegetables.
The Tuscan Bean & Rice acts like a Solid, like the Clam Chowder, the -Fire Roasted- Southwestern Vegetables acts like a free flowing liquid.
The Tuscan Bean lost by a few or more seconds, making the Southwestern Vegetables the winner!!!
=)
It’s awesome!
Thanks!!!!
Tori Branand, Age 12
Wow… I tried to pick one that you would easily find. You just need a gloppy one that is solid. Even a can of re-fried beans can work if the cans are about the same. Cream of mushroom is a solid in the can when you open it, right? So that could work, too… let me know what you found!
Believe it or not …. I can NOT find Campbell’s Clam chowder. What would be a good substitute? I was thinking maybe Cream of Mushroom or Tomato?
This is experiment is really cool!!!
Holly Thomson age 11
I love this experiment! It’s so fun to watch the cans race!
🙂 times 1,000000000000000000!
sevy keble