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 Subject: Ferris Wheel Physics Category: Science Asked by: seabrook-ga List Price: \$10.00 Posted: 27 Feb 2005 06:11 PST Expires: 29 Mar 2005 06:11 PST Question ID: 481734
 ```HI, my 12 year old daughter has chosen a science fair project on the ferris wheel. She needs to be able to explain "why the passengers dont fall out of the car while the wheel makes it's revolution. (Especially when it reaches the top. We both have a very limited knowledge of physics. Understand that inertia,hinges and pulleys have something to do with it. Can you help in explaining these concepts on an elementary level? She has to present a research paper. Also would like to know how to construct a model wheel to explain her theory that it takes a combination of gravity, hinges, and body weight, etc. Need to use household items. Please help. project due soon.```
 Subject: Re: Ferris Wheel Physics Answered By: maniac-ga on 27 Feb 2005 08:57 PST Rated:
 ```Hello Seabrook, OK. Let's address the question in a few parts - constructing the Ferris Wheel - the "physics" of a Ferris Wheel - getting the Ferris Wheel to school - other resources that may be helpful Constructing the Ferris Wheel There are three main parts that need to be made: - the frame to hold up the wheel - the wheel itself - the cars that hold the passengers I assume the wheel will NOT be motorized and your child can turn it by hand. Make a clarification request if you want ideas on how to drive the wheel. I also assume you do not want to use a construction kit like Knex (which does have a ferris wheel model) The frame needs to be reasonably strong but open. A narrow / tall cardboard box could be cut to make the frame (an "A" frame or inverted "T" or "Y" shape). A dowel (or a long nail or a round stick from a hard candy) serves two purposes - the pivot for the wheel - holding the two parts of the frame apart / strenghtening the frame The pivot does not have to turn so it should be taped / glued to the frame after the wheel is installed. You could build a frame from any suitable material, wood (even balsa) for example would be good. I recommend cardboard since it should be strong enough and easy to cut / fold / glue into the right shape [plus the only balsa I ever bought was for science projects]. The wheel is an interesting problem. You may get away with something as simple as plastic straws (available from the grocery store / not the bendy ones) for the spokes of the wheel. A 10" straw could have a hole at the midpoint (to go through the pivot) to form a relatively small wheel (10" diameter). If you have bendy straws, cut off the bending part and use a hub. If your pivot is too large or you want a larger wheel, something else must be used to serve as the hub. The cardboard from the back of a pad of paper is one alternative. Again balsa wood or some other material would work as well. Cut to shape with a hole in the center. Around the outside, I would use the same type of material (e.g., straws) to connect the spokes. If you use round toothpicks as the pivots for each car, tape or glue the toothpicks to the straws (small holes in the straw ends). I suggest you lay out each wheel on a table and make everything fit before starting to assemble the wheels / pivots / cars. I would also suggest a simple "guide" to make sure the wheels are round. Something as simple as a circle drawn with a pencil / string will help with layout and assembly to make the wheel turn more smoothly. The cars do not need to be very strong and could be made from paper / perhaps colorful paper to make the wheel look more interesting. The cars could be "A" shaped with a pivot hole at the top of the A and the passenger holding part of the car at the bottom of the A. Other shapes should work as well as long as most of the weight is on one side of the pivot hole. Put a relatively large hole (compared to the car pivot) to make sure they turn freely. Assembly should be straight forward once all the pieces are made. Something like - assemble the two wheels (but not yet connected to each other) - place pivots / cars to connect the two wheels [confirm the cars pivot freely] - put assembled wheel onto main pivot and secure onto the frame You may want to decorate the pieces prior to final assembly. I would try to avoid having to work on the wheel once it is assembled. If you want to have passengers "fall out" as described in http://www.nwrel.org/msec/nwteacher/spring2002/lingua.html [about 2/3rds of the way down] you could fix one (or two) of the cars so it does not pivot. If you do this, passengers should be something light (that will not break nor break the wheel when they drop); perhaps a paper cutout. I also found a nice picture of a Ferris Wheel made by an 8th grade student at http://www.ebecri.org/custom/hopkins%20rides.html (down near the bottom) Ferris Wheel Physics Much of the material on the web on "Ferris Wheel Physics" is written by college students for their reports (college level physics). The main reason the people do not fall out is that described by "siliconsamari" (the wheel moves too slowly). It is a little more complicated than that however. When the wheel is stopped, gravity pushes the cars so they are below the pivot. As the wheel spins, the inertia of the cars makes them want to "fly out" from the center. This effect is actually enough to measure, for example: http://home.snu.edu/dept/physics/frontier/presentations/Ferris%20Wheel.ppt describes a project done by college students to measure the effect. The effective force on each car (or passenger) is equal to the "sum" of the forces. So we have: - gravity pulling down - the spin / inertia pushing out from the center so the resulting force will vary as you go around the wheel (in both direction and magnitude). The magnitude in the vertical direction (preventing you from falling out) looks something like a sine wave, centered on "one G" and the minimum is well above "zero G". I would check several of the sites found with phrases like ferris wheel physics or ferris wheel physics and look for charts that illustrate this as well (be sure to reference the original sources in your report!). Consider the pivot (for the cars) to be a "hinge". Note that the pivot allows the car to stay oriented "down" so the passengers are safe. You can illustrate this with the "fixed" car as suggested before. For a pulley, that is sometimes used in the Ferris Wheel to spin the wheel. I have seen other wheels that are spun with gears instead. The pulley is attached to the hub of the wheel, the loop goes to another (much smaller) pulley on the motor, and as the motor spins the wheel will spin as well. The ratio of pulley sizes will help control how fast the large wheel spins. Getting the Ferris Wheel to School My oldest son (now 16) discovered that it is HARD to get a large project to school on the bus. He also did not figure this out until it was too late and had to fix it at school. A few tips: - smaller is easier to transport - a repair kit (an extra part or two, glue) should be brought just in case - a sturdy box / padding can help - a bag around the project to catch pieces that fall off or break - some assembly at school is OK but practice at home Note that mom / dad could take the project to school - but I do not know your circumstances. [I know I didn't do that...] Other Resources Knex toys (available from several sites) http://www.iqkids.net/knex.html The Ferris Wheel kit is in the lower right (may need to scroll) and was priced at about \$50. Has a nice picture of the assembled kit. "Amusement Park Physics" (ed. Carole Escobar, pub. Amer Assn of Physics Teachers, 1994) See if your local library (or college library) has a copy of this book. Search phrases for more information: Ferris Wheel Physics Ferris Wheel Physics "high school" Newton's laws elementary explain [put a physics phrase here like inertia, hinge, pulley, ...] elementary science project elementary science project ferris wheel "high school" science project knex ferris wheel Please make a clarification request if some part of the answer is unclear or you need additional information on some part of the answer. --Maniac``` Request for Answer Clarification by seabrook-ga on 27 Feb 2005 10:02 PST ```Thank you for your help. I have a better understanding of how to make the A frame. Difficult to visualize the construction of the rest of the model..... Liked the picture of the wheel made by the eigthgrader. Do you know what materials were used in that model? It looks like some type of metal. What would we use to make the car hang freely from the metal bars between the two wheels. Unable to tell where the round toothpicks fit in. I saw your note to put a hole in the top of the paper car. How and what would we use to attach the car to the bar? Are you able to diagram the construction of the car? Show how it is attached to the bar between the spokes? I really am a physics and design dummy. YOu kept mentioning pivot and pivot hole.? Pivot for the car and pivot for the frame? Where is that? That is the part that I am not understanding. Thanks again. Smart in other areas!``` Clarification of Answer by maniac-ga on 27 Feb 2005 11:35 PST ```Hello Seabrook, Let me take the follow up points in order. #1 Difficult to visualize the construction of the rest of the model. It would be nice to have a step by step assembly guide on line, but I could not find one. I believe you understand how to make the frame. For the cars, they can be just about any shape as long as they have a loop (or hole) on top to mount onto the bars that separate the two wheels of the Ferris Wheel. I was thinking something shaped like an open top bag with handles but another shape should work as well. To make the big wheels of the Ferris Wheel, I would start with a circle (say on a big sheet of paper) with the diameter matching the length of the spokes. If you use 10" straws, that would be a 10" diameter circle. Mark the center as well. Lay the spokes (let's say 8 of them) evenly and measure the distance between the spoke ends to figure out how long the outside pieces will be. I would build one wheel as a "sample" and make sure it spins smoothly before you build the second wheel (or throw the first away & make two new ones more carefully). Once you have two wheels you need to separate them by a short distance with the pieces that will hold the cars. I suggested using toothpicks - below you mention "metal bars". I am not aware of any "easy" way to do this assembly step - other than having two hands hold the wheels in place while another person separator pieces and cars into place. This should give you the wheel assembly, ready for mounting on the base. Putting the wheel onto the base should be similar to putting a wheel onto a bicycle. #2 Do you know what materials were used in that model? It looks like some type of metal. Look at http://www.ebecri.org/media/MVC-011F.JPG for reference [apparently the picture on the web site has MUCH more detail than what you see on the page...] I cannot be certain but... - the frame looks like a premade bar - I have seen thin steel bars drilled like that (but not a "household item") so you are probably correct. The axle may be a threaded bolt. Also note there are reinforcing bars between the A frames low in the picture (appear to be glued on). - the spokes are attached to a hub - perhaps a thick wooden dowel with a hole in the middle for the axle (or as I said before "pivot for the wheel"). The hub could also be a cardboard tube (like for paper towels) but then you would need end covers with holes for the axle. Cannot be sure of the spoke material - could be wooden dowels, plastic straws, or something else. Note also the reinforcement pieces - I believe this was necessary due to the size of the wheel. If the wheel is relatively small (like the 10" one using straws) the reinforcement may not be necessary. - the chairs (or cars) appear to be a combination of paper and pipe cleaners. Again it is hard to be sure. Much of the Ferris Wheel appears to be glued together other than the frame which appears to use threaded bolts and nuts. #3 What would we use to make the car hang freely from the metal bars between the two wheels. A loop (or hole) of some kind. Expanded more on #5. #4 Unable to tell where the round toothpicks fit in. OK - metal bars (perhaps pieces of a wire coathanger) would work. Otherwise, replace the "metal bars" between the two wheels with toothpicks. [I was trying to use "household items"] #5 I saw your note to put a hole in the top of the paper car. How and what would we use to attach the car to the bar? Are you able to diagram the construction of the car? Show how it is attached to the bar between the spokes? Diagrams are hard when using text only and I did not find a suitable picture. I was thinking of something like a bag with handles for the car and the toothpicks (bar) serving two roles: - separating the two wheels of the Ferris Wheel - going through the loop (or hole) to hold the car in place Note that if you take a bag with handles and put your arm (or a dowel) through it, the bag should rotate smoothly. You could cut a piece of paper / fold it to make a "car" with the hole on top to put the toothpick (bar) through. Another way to look at this is a curtain rod (separating the wheels) and the hooks that hold up the curtain. From the picture example - if they used pipe cleaners, you would make a loop with the end of the pipe cleaner to go around the bar separating the two wheels. #6 You kept mentioning pivot and pivot hole.? Pivot for the car and pivot for the frame? Where is that? That is the part that I am not understanding. Think axle for the wheel for the "pivot for the frame". [and in retrospect I should have used that word...] The "pivot for the car" works in a similar way. The bar between the wheels that holds up the car is what I was referring to. It is important that the car move smoothly on the bar (or pivot) - that's why I used pivot instead of "separator" or "bar" or some other term. Good luck with the project and let me know if you need further clarification. --Maniac ?```
 ```people don't fall out because the wheel turns so slowly that they never come near the speed which would overcome the force of gravity which is pressing them down into the seat. This does happen on some rides.```
 ```The ferris wheel is a complex ride so in this try to find some chicken wire, and rubber bands, a nd swining materials to make this . it should be fun, and remember to work together```
 ```Erector Set Toys makes a ferris wheel kit. Try NorthPoleToyShop at http://northpoletoyshop.com. Click on the erector link. It is about \$70.00```