HOw do i build a joule mobile mass transporer?

chickentown · Post by **chickentown** » Sun Jan 21, 2007 2:56 am

I have assigned this physics project which i have to construct a car that
able to transport a 1 kilogram mass for a particular distance using the energy that is released from the 1 kilogram mass when it falls a distance of 10 centimeters.
I just only know that I need to build some sort of car but I'm like clueless about what am i gonna use for this constructions and how it suppose to look like.. Some people in my class said that they gonna use some kind of lever attacht with the car .... but I still don't get the idea to start
So anyone have any idea to help me build this car. My goal is to make the car goes 8 m long. Please help me with this, my grade totally depends on this..

jamescjb · Post by **jamescjb** » Sun Jan 21, 2007 7:22 pm

Hi,

Really interesting project!

OK, I think the project is about the exchange of energy from potential energy (the drop of 1kg mass) to kinetic energy(the motion of the car). The success of making the car move 8 meters long depends on how much energy it exchanges. In my point of view, the loss during exchanging is what we should deal with. Of course, the design of the car system is important as well.

What I am thinking right now is to find a suitable weight for your car. As we are going to use the inertia of your car by weight, it cannot be too light. However, if the weight of your car is too heavy, the friction between the wheels and ground will increase as the formula memtions(http://regentsprep.org/Regents/physics/ ... efault.htm).

After you know how much weight your car should be, you should think about the type of car's wheels. To reduce the friction, I don't recommend to use rubber wheels, but I do would like to use old or used CDs. The CDs have light weight for sure, the point is they have really small touch area with ground.

About the design of your dynamic system, I am thinking to use some kind of springs, but I am still thinking.

Please tell me when you have some ideas of your car design, I would like to help you as much as I can.

Once again, good luck on your project!

chickentown · Post by **chickentown** » Sun Jan 21, 2007 11:41 pm

hi jamescjb , thank you for your help.. I kind of think of use cds for the wheels too. about the car I think I might use a rectangle wood for the base (is it good or should I use a rectangle base)?I am thinking of a car similar like mousetrap car which its structure would help for the distance..But I still don't understand how could I transfer the 1 kg mass object as the energy for my car??? What should I use? construct some kind of pulley or lever? If so, how can I attacht it to the car. And one more thing what do you think I should use to make axles .

I'm sorry if I ask too much, but would you please help me... I really need some help. If possible can you show me how? Thank you very much.

chickentown · Post by **chickentown** » Mon Jan 22, 2007 12:03 am

and if I want to build a pulley that goes with the car , then what materials do you think I should use ?

jamescjb · Post by **jamescjb** » Mon Jan 22, 2007 12:38 am

I'm really glad that you have thought about for your project so much. Rectangle base is not a problem, but it depends on the material you are choosing. For me, plastic base is easy to get, simple, firm and not so expensive. You can get a plastic base from a toy car(those little battery car's base). If wood works for you, it is fine.

I just have some questions. Is there any specific requirement for the 1 kg mass? And do you actually carry the 1kg mass during movement? By the way, I wonder on what kind of material is your car going to be running, on a wooden desk, or glass table?

If you want to use pulley, do you mean you are actually using the 1kg mass to pull your car and make it roll 8 meters?

It will help more if you would like to tell me the specific requirement.

deleted-71576 · Post by **deleted-71576** » Mon Jan 22, 2007 9:22 am

Using CDs for the wheels is commonly used in mouse trap cars. They work very well.

Give us some more details, and we can give you some suggestions.

BTW, try to think "out of the box" on this type of project. It tends to become much more rewarding, memorable, and also tends to be graded higher.

chickentown · Post by **chickentown** » Mon Jan 22, 2007 4:53 pm

hi , jamescjb
Yeah , all the car's parts including the 1 kg mass must stay together during the entire trip and I think it would run on a cement floor ( actually on a stage ) And for the pulley , yeah I've thinking to use the pulley to transfer the energy from 1 kg mass as the energy for the car to run.
I think I'm gonna build a pulley in the middle of the car, because when the 1 kg mass drop it needs to be on the car . But the problem is what should I use to make this pulley and how am i gonna attacht it to the car??? I am still unsure about that.
So, If you could think of something , it'll be very nice of you to help me
Thanks for all your suggestions ..
Following is the intructions if you'd like to know
Joule Mobile Mass Transporter

The Objective is to build a device which will transport a 1 Kg mass a distance of 10.0 meters over a level surface (as level as possible) using the energy released as the 1 Kg mass falls a distance of exactly 0.100 meters.

Rules:

1. A 1 Kg mass cyclinder (you will be provided with the dimensions in class) with a hook on top will be supplied for use in the competition. The mass must be carried (not rolled or dragged across the floor) by the transporter.

2. The energy to run the transporter is to be stored by lifting the mass, vertically, 10.0 cm above the place (which must be parallel to the floor) where it will rest on the transporter at the end of the run. The mass can not move or rest on a slant with relation to the floor. The force of the falling mass will propel the transporter. Since the falling mass is to supply no more than one joule of energy to the transporter, care should be taken to see that its center of mass does not fall greater than 10.0 cm and that it does not swing during the movement of the transporter.

3. All parts of the transporter, including the falling mass, must move with the transporter and cross the finish line.

4. The transporter must stop on its own using only the friction provided by the wheels and the floor surface. There will be no braking mechanism.

5. After the transporter begins to move, it must be self guided. If it does not move in a straight line, the component of its motion in the designated direction will be measured as the official distance covered. If a part falls off the transporter, then the component in the designated direction to that part will be measured.

6. If a rule clarification seems to be required, it should be discussed with your teacher before the due date. "Cute" solutions which meet the letter of the rules but which violate the spirit of the contest will usually be judged unsatisfactory.

Grading:

120 points
40 points will be determined by workmanship/ design
80 points will be determined by its performance or functionality

deleted-71576 · Post by **deleted-71576** » Mon Jan 22, 2007 6:19 pm

I originally thought about throwing the weight which yanks the car attached by a string behind it, but your rules forbid this. Pity.

I would think you would want to design some mechanical advantage into your axle. Basically the equivalent of gears, but done with varying the size of the axle where the string is pulled.

This is a link with a Lego version of your experiment. Sounds like what you are proposing - pulley in middle of car, weight drop pulling a string, etc.

http://www.marshall.edu/LEGO/Miller/14F ... iller.html

chickentown · Post by **chickentown** » Sun Jan 28, 2007 12:49 pm

can i anyone have any idea? my car only went 3 m, it's not enough

And I don't know why it did not work... I used Cds for wheels, pulley in the middle , platform in the middle , does it have to be straight or slanted and does it have to be right in the middle or to the back wheels a little bit. and for the wheels , are they have to be the same size or the back wheels have to be bigger in order to give more forces...

Louise · Post by **Louise** » Sun Jan 28, 2007 2:37 pm

chickentown wrote:can i anyone have any idea? my car only went 3 m, it's not enough And I don't know why it did not work... I used Cds for wheels, pulley in the middle , platform in the middle , does it have to be straight or slanted and does it have to be right in the middle or to the back wheels a little bit. and for the wheels , are they have to be the same size or the back wheels have to be bigger in order to give more forces...

Why don't you use the information from your test run to try and figure out what went wrong. For example, did the wheel wobble? Was is going very slow? Did something rub against the wheels and slow it down? Did the weight catch on something when it fell?

Depending on the physics of your setup, I would expect it should go straight. Did it go straight, or was its path curved... this might tell you something is unbalanced.

Also, you could try some of the modifications you suggest... that is the scientific method in action. Try larger wheels. Does it help? Why? Doing these simple tests will help you understand things better.

Louise