joule mobile mass transporter

ahmee · Post by **ahmee** » Tue Jan 23, 2007 5:53 pm

Hi chickentown,

For the string, I just used regular string that my teacher gave me. And I attached the stick of wood in the middle by drilling a nail from the bottom of the car and up into the wood. You could also use superglue. =)

chickentown · Post by **chickentown** » Tue Jan 23, 2007 8:13 pm

thank you ahhmee, this helps a lot

And sorry for asking too many questions but just one little thing, what was your the car body 's dimension( I think about 15*25cm, is it good or it 's a little big ).

chickentown · Post by **chickentown** » Tue Jan 23, 2007 8:14 pm

what I mean is the dimension of the piece of wood you used for the body car...

ahmee · Post by **ahmee** » Tue Jan 23, 2007 9:46 pm

Hi chickentown,

I'm sorry. I don't know the exact dimensions of mine, but I'm going to say the dimensions were like a regular hardcover book.

chickentown · Post by **chickentown** » Wed Jan 24, 2007 12:32 am

hi ahhmee, the hardbook cover, is it a little too big cause I think the less heavy the faster the car would go, is it right. I've thinking I would use a 15-27 cm dimension, what do you think ??? Is it okay..
By the way thanks for your help

chickentown · Post by **chickentown** » Wed Jan 24, 2007 12:37 am

Sorry to bother you , but for the axles... What did you use ? Some of my friends said that they could it be sleeve tube? How do you make it fit with the CDs holes ( buy the exactly size with the holes??? or use some other thing to make it tight.. ?? )This probably the last concern I have, thanks for your patient..

ahmee · Post by **ahmee** » Wed Jan 24, 2007 1:52 am

Hi chickentown,

Yes, the car would go faster if it is less heavy. So basically, try to make your car as light as possible, but heavy enough so that it's steady; it won't topple when you put the 1 kg weight on it. I think your dimensions are ok.

For the axles, I'm not sure what I used because my dad helped me on this part. But, you can use a round stick that's about the same size as the hole in the CD and glue it together. And I think you can also use sleeve tubes that are maybe a bit smaller the size of the CD holes because you need to be able to fit the tube through the hole. If it's the exact size, then you wouldn't be able to put it through the hole.

Good luck! =)

deleted-71588 · Post by **deleted-71588** » Wed Jan 24, 2007 6:53 am

As far as string goes, you want something that is strong enough and is in scale with the size of your vehicle and that will withstand any wear it will get during your experiments.

Since you are dealing with 1Kg (2.2 pounds), something like a 12 to 15 pound test fishing line might work.

A lumber yard might give you a short piece of twine they provide to customers to tie down materials they sell if you want something larger in diameter.

Part of experimenting is scrounging things that will work that are available at little or no cost.

deleted-71576 · Post by **deleted-71576** » Wed Jan 24, 2007 7:49 am

Things like plywood used from model shops would provide a strong, very lightweight car body. Very thin, very strong, and pretty aerodynamic.

You don't want the weight to destroy the car when it lands hard, so a little foam where the weight would hit could be helpful as well. I think a light, strong car would serve you well.

chickentown · Post by **chickentown** » Wed Jan 24, 2007 6:39 pm

ahhmee, thanks for your help, my car is looking pretty good now, but I am still unsure about the height of two stick of wood in the middle of the body car ( pulley stand )-- how high they need to be if the 1 kg mass has the height of 7cm ??? In addition to the 10 cm height drop and the string length to hold the mass, so do you think 25 cm height is appropriate for the two wood sticks???
Once more, thanks all for your helps

ahmee · Post by **ahmee** » Wed Jan 24, 2007 6:43 pm

Hi chickentown,

The height of the stick of wood should be .100 meters - the height that you are going to drop the weight.

chickentown · Post by **chickentown** » Thu Jan 25, 2007 7:17 pm

hi ahhmee, for the string of the pulley; we have to tie it to the axles right?

ahmee · Post by **ahmee** » Thu Jan 25, 2007 7:31 pm

Hi chickentown,

Yes. You have to tie it or attach the string somehow to the axles in order for the car to move when you drop the weight.

chickentown · Post by **chickentown** » Thu Jan 25, 2007 9:19 pm

hi ahhmee, I tested my car, it woudn't move , I don't know why?? Is that right that you put the axles under the body car right??? It 's not moving but when I lift the back up a little bit then the wheels start to move. But it is not moving when the wheels on the ground??? Would it because my axles are too low ??? cause under the body I put a piece of wood that have holes then stick the axles through the holes... ?? Is it right??? Oh my god the due day is tomorrow, I don't know what to do...

chickentown · Post by **chickentown** » Thu Jan 25, 2007 9:32 pm

I think I figured out why, I think it because the axles are too low, because I did not the piece of wood with holes aside the body wood but under it.. But I don't think I have time to fix. Ok well, tomorrow only the predue day which it have to run 2 m in order to have 20 points, so i'll just take 10 points then fix it on the weekend.... Tomorrow I have a bigg Benchmark for Precal so I need to study

ahmee · Post by **ahmee** » Thu Jan 25, 2007 9:45 pm

Hi chickentown,

Yes, I think your car didn't move because the axles were too low. So maybe there was too much friction? But I'm not entirely sure. Does anyone else know?

chickentown · Post by **chickentown** » Thu Jan 25, 2007 9:49 pm

so , as for your car, you stick piece of wood with holes at each corner of the body wood right? like some of the mousetrap car on google image ???And then put the axles through the holes??? I think so too. but too bad I don't have time to fix it..

ahmee · Post by **ahmee** » Fri Jan 26, 2007 3:14 pm

Hi chickentown,

Yes, that was pretty much how I did wheels part of my car.

chickentown · Post by **chickentown** » Fri Jan 26, 2007 7:59 pm

hi ahhmee, I tested again today with the 1kg mass and it went 2 m only. My teacher said that the bigger the axles are, the more work it'll give . is that right? So, do I need to make my axles bigger since my axles are just a big as chopsticks. Do you think so??? And for the wheels , you only used 4 CDs right? cause some of my friends sticked 2 CDs as 1 wheel.. Which way do you think would work the best?? Are all four wheels the same size or the wheels with the strings wind on its axles have to be smaller than the other wheels???? I'm not sure but I saw some of Joule mobiles that constructed like that and they went pretty far.... Do you know any other materials that can make the car goes farther???? And for the reel , where do you get it, what size is it? Cause the one that I use is as big as the CD... Can you give me some suggestions to fix my car?

chickentown · Post by **chickentown** » Sun Jan 28, 2007 12:41 pm

HELP HELP, MY CAR ONLY WENT 3 M, CAN YOU HELP ME FIX IT?? WHAT CAN I DO??? HOW DID YOU DO YOUR CAR EXACTLY? CAN YOU TELL ME? I DID THE SAME THING AS YOU TOLD ME BUT WHY? IS THAT THE PLATFORM ( STAND ) HAVE to be right in the middle of the car or a little to the back wheels? Does it have to be slanted or straight???
Oh my god, tomorrow is the last day

deleted-71576 · Post by **deleted-71576** » Sun Jan 28, 2007 2:33 pm

You want the center part of the axle where the fishing line (or string) goes around to be of larger diameter. The diameter of the axles where they attach to the CDs should be far less important. By enlarging the axle diameter where the line wraps around, it acts like you have a higher gear on the car. Slower to start, but will go farther.

deleted-71576 · Post by **deleted-71576** » Sun Jan 28, 2007 2:38 pm

You also want the weight to drop the full distance. I think the advice you got earlier has the weight falling a smaller amount. Measure the distance from the same spot on the weight (where it attaches would be easiest) when it is at the top of the stand and when it is at rest at the bottom. That distance should be the maximum you are allowed.

You should also try to reduce the friction of the axles on the car. Any good lubricant (Spray Teflon would be best, furniture polish, etc would help. Sanding the axles smooth will also help if they aren't. With this type of device, the friction really hurts.

chickentown · Post by **chickentown** » Mon Jan 29, 2007 12:46 am

where can i get spray teflon????

deleted-71576 · Post by **deleted-71576** » Mon Jan 29, 2007 4:28 am

I found some in a hardware store. Bicycle shop would be next best.
Super Lube is the brand name of the hardware store variety. Bike shops have multiple chain lubricants that have Teflon or Krytox (similar to Teflon). Brand name there is Krytech. GT85 could work too, amongst others.

Alternatively, you could find powdered Molybdenum Graphite in a hobby store. It's the stuff Cub Scouts use on their axles for the Pinewood Derby. Messy stuff, and it needs to be put on just before your run, but it's quite effective too.

Sondinh · Post by **Sondinh** » Sat Dec 01, 2007 4:14 pm

Hello there Ahmee,

My physic project is due on December 6, 2007. It is a Joule car project. The object of this project is to design and build a device that will transport a 305 grams can of Tomato Soup Can a distance of 4 meters over a level surface. The energy to propel the Transporter originates from Gravitational Potential Energy by replacing the soup at a height of 0.2 meters above its resting point. The maximum dimension is
Height: 30 cm Width: 30 cm Length: 30 cm

Please give me a detail list of the things I need to buy in order to build this Joule car. Also if you have pictures of it, can you please send it to [email protected] (they will forward it to me).
Please summarize the steps on how you made this project. Thank you so much!!

bradleyshanrock-solberg · Mon Dec 03, 2007 7:03 pm

I've done this sort of project and any string strong enough to hold the weight should do fine. We used rubber bands for the power source rather than dropping a weight, but we used ordinary string for the brake and to hold the tension of the rubber band. The forces you're talking about are a lot less.

I think something like what you'd use to tie up a small package of that size would be fine, the ordinary white stuff that rolls up in a ball. But kite string, fishing line or anything else that is lightweight, easy to tie and isn't likely to deform with repeated uses of dropping the weight should work fine.

Coarse twine or yarn would not be a good choice.

There are a lot of possible ways to attach the rope to an axle, but an example might be to drill a small hole through the axle and run the string through, tie it off. Then just roll the car backwards on the ground until the weight is in the "up" position. This approach will require 4 meters of string however as when you reach the end, the cart will stop, and given the height limits, you'll need to rig it to only raise the weight near the end of the 4 meters of "backing up" or use big gear ratios.

It might be easier just to wrap the string around the axle, raise the weight and have the string release when the weight hits bottom, relying on momentum to get you the remaining distance. How well that works will depend on how good a "grip" the string has on the axle and how good a job you've done with preventing friction on the wheels (if you push the car, how fast does it slow down and stop?)

Regarding "I made the cart, why won't it move".

The reason is that there are two kinds of friction.

Without going into too much detail, imagine a brick on a board. You can tip the board up and the brick won't move. As you increase the angle, the brick will start sliding. The interesting thing though, is you can get the brick to slide earlier, on a lower angle, if you nudge it.

For whatever reason, the force required to get your car moving is greater than that exerted by gravity on your weight. You need either a heavier weight or less friction in your car wheels or the car needs to weigh less.

(less overall weight on your car helps because friction is partly a function of how much weight is exerted, and also because it takes more overall energy to move a heavy object than a lighter one).

Lifting the back up means that the weight only has to spin the wheels....it doesn't have to move the whole vehicle. Do everything you can to reduce the weight of the vehicle or, if allowed, use a larger weight.

There are some other things you can try if that doesn't work or you can't do it.

1. try greasing the axles...so it takes less force to cause the wheels to spin. But only in the part where the axle touches the frame...not the part where your string is wrapped around the axle.

2. change axle size to get a mechanical advantage. If you have a thicker axle where the string is wrapped, the same amount of string moving will exert more force on the wheels to move the cart. This is the same concept used by an automobile in "low gear" going up a hill, or in a 10 speed bicycle when you change gears to make it easier to go up hill (low gear) or to go faster downhill (high gear) You might also try using smaller wheels to get a similar effect, but that may make it difficult to move 4 meters. There is a trade-off here....high gear will push the car further per revolution of the axle but takes more force to get the axle to move at all. low gear will require less force to turn the axle, but the car won't go as far.

Hopefully these ideas can help. Without seeing your actual car, or the tools/materials you have to work with it is hard to give specific advise.

joule mobile mass transporter

(Joule Car )Help ASAP!