# Homework Help: Ideas and throughs on engineering task.

1. Aug 8, 2009

### Gustaviito

So basically I've been given a task to do. I have done lots of research, but I also think that asking the perspective of other people would be a good way to brighten up my ideas and options.

Simply, my task is:

Develop a vehicle, where the only source of power is a rubber band. The vehicle will have to carry a load (around 2kg) and must cover a distance of at least 1 meter.

Thoughts and ideas on materialsto use, physics to consider, and other useful advice would be GREATLY appreciated (:

2. Aug 8, 2009

### fleem

It really depends on what other requirements there are (cost, toughness, demonstrating your knowledge, etc.). You could easily slap this together in a few minutes with legos or tinkertoys, but I'm not sure that would be impressive enough.

3. Aug 8, 2009

### Gustaviito

Ok Ok. I should add that this is a competition, as well as a task.

The vehicle that goes the furthest distance obviously will get the better marks.

So how can I maximize energy input and correspond that to maximizing the distance. Don't forget load.

4. Aug 8, 2009

### fleem

Just some random thoughts...

Surgical rubber.

Mass of the rubber is proportional to total energy it can hold, so ideally the rubber weighs notably more than the payload and vehicle.

Choose a wheel diameter and optimal speed (depends a lot on terrain texture), then adjust rubber length/width accordingly so hopefully you won't need gearing (Buy thinnest available because you can always double it up). You'll probably want to empirically adjust the rubber length/width ratio.

Also dependent on terrain: Consider widely separated wheels rotational locked together onto one shaft, to help keep it going straight. Have a strategy to make them be exactly the same diameter!

Lubricate the rubber, especially if its doubled up.

If the surface is rough, consider a flywheel and gear down and move slowly (assuming high efficiency gearing and a ratchet). Otherwise it might be better to get up a little kinetic energy and coast the last part, but not so much that you need good traction at the start (which translates to those inefficient soft sticky tires--something to be avoided, otherwise).

If speed gets you points, then most of the weight on just one or two tires (a drag rail comes to mind), and less efficient sticky rubber tires. (But it looks like speed isn't an issue)

5. Aug 8, 2009

### Gustaviito

Thanks a lot mate!! Appreciate it !

6. Aug 8, 2009

### Staff: Mentor

Please include a pointer to this thread in your bibliography for your project. It's important to provide accurate attribution in your projects.

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