Science project : Foam vs Rubber
12-27-2004, 02:00 PM
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RE: Science project : Foam vs Rubber
You can study the traction differences between the two using same car, surface and measure the time over distance, but not too sure on keeping other variables at bay. Keep it simple! Do not know wht academic level your project or credit is aimed at.
Good luck!
Good luck!
12-27-2004, 03:27 PM
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RE: Science project : Foam vs Rubber
High school level - something simple wuld be awesome but i dont like too simple stuff, and i was gunna do traction, but then i realized..i didnt know a way i could use to measure traction.
Please help me, but not too easy either....im not a 4th grader ;D
Please help me, but not too easy either....im not a 4th grader ;D
12-28-2004, 03:22 PM
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RE: Science project : Foam vs Rubber
I would construct a traction test rig where I would have samples of each surface mounted to 12 x 12in boards (i.e. glass, asphalt rough, asphalt smooth, asphalt wet, hard dirt, soft dirt, concrete etc etc)... Place the car on the surface attached by line at a fixed point on the chassis and then thru a pulley and attached on the other end by to a drop weight off the side of a workbench or table.
You might have to have some kind of "release" mechanism to hold the pulley once the fixed weights are suspended. This is to ensure that you control the variable of "initial shock load" so that all test runs are the same and you aren't dropping the weights during some tests and gently releasing them on others... I would hold the "adhesion" variable to a simple "instantaneous loss of adhesion" The applied weight at where the car actually 'budges" from a stationary position, and not something like sliding distance or sliding speed over time, that has too many variables to try and control. Do numerous trials and take the average get a nice large sampling of data for each surface...
Attach the line to the car at as low a point as possible on the chassis to reduce the "lever" forces (the car will be induced to "lean" if you attached the line say, at the top of the carry handle) But then again, attachment point will be a good additional experiment for making general observations on the effect of suspension on the cars cornering adhesion.
You can have fun and measure from left side and right sight and front and rear... With the brakes applied fully of course for the the front and rear tests. You might also make the test a bit closer to practicable application by having a small motor pull the car slowly forward while applying the side load, the point where the tires are pulled sideways over a fixed line is where you make your measurement for adhesion comparisons... i.e. foam was pulled 6 in before crossing the line as opposed to rubber which was pulled 3.5in before the tires were pulled over... You can refine on that of course...
There are SO many variables involved (just as in the full sized case) that only the most general of conclusions can be drawn from such an experiement, since you aren't factoring in things like suspension tuning, vibration, temperature variations, variations in compounds between manufacturers...
At best you should call the experiment one of "adhesion" more than one of traction, since traction is a term that applies to useable grip in a practical application (while the car is actually in use, or racing)
If you're going for the grade, then I think if your science teacher is worth his salt, he will be more impressed by how intelligently you try to account for and define the experiements boundaries and limits, then the fact that the rc car is "cool" *laughing*
Don't make sweeping statements like "the foam tires are grippier so the car will be faster" that is a HUGE leap! Stick to what the experiement tells you directly and try to infer intelligently from that. Just as in real life many things are counterintuitive, and as an example, tires that have less adhesion may actually yield faster lap times in certain situations because the car is more "controllable" and less prone to snap spins than high grip counterparts, or another would be that the rubber tires might have less adhesion than foam tired, but on bumpier surfaces are far more compliant (deal with undulations and debris better)... When you make a comparison, alsways make certain it is a "comparision" and not something I see all the time like "X is better..." Better than what? and what do you mean by "better"?
For a practical test, use a large circle and drive around 10 or 20 times for a timed run. But this is much more involved as you would need to have to go out and find suitable locations...
Have fun! and whatever you do, don;t mix science with religion!!!!! *laughing*
Feanor
You might have to have some kind of "release" mechanism to hold the pulley once the fixed weights are suspended. This is to ensure that you control the variable of "initial shock load" so that all test runs are the same and you aren't dropping the weights during some tests and gently releasing them on others... I would hold the "adhesion" variable to a simple "instantaneous loss of adhesion" The applied weight at where the car actually 'budges" from a stationary position, and not something like sliding distance or sliding speed over time, that has too many variables to try and control. Do numerous trials and take the average get a nice large sampling of data for each surface...
Attach the line to the car at as low a point as possible on the chassis to reduce the "lever" forces (the car will be induced to "lean" if you attached the line say, at the top of the carry handle) But then again, attachment point will be a good additional experiment for making general observations on the effect of suspension on the cars cornering adhesion.
You can have fun and measure from left side and right sight and front and rear... With the brakes applied fully of course for the the front and rear tests. You might also make the test a bit closer to practicable application by having a small motor pull the car slowly forward while applying the side load, the point where the tires are pulled sideways over a fixed line is where you make your measurement for adhesion comparisons... i.e. foam was pulled 6 in before crossing the line as opposed to rubber which was pulled 3.5in before the tires were pulled over... You can refine on that of course...
There are SO many variables involved (just as in the full sized case) that only the most general of conclusions can be drawn from such an experiement, since you aren't factoring in things like suspension tuning, vibration, temperature variations, variations in compounds between manufacturers...
At best you should call the experiment one of "adhesion" more than one of traction, since traction is a term that applies to useable grip in a practical application (while the car is actually in use, or racing)
If you're going for the grade, then I think if your science teacher is worth his salt, he will be more impressed by how intelligently you try to account for and define the experiements boundaries and limits, then the fact that the rc car is "cool" *laughing*
Don't make sweeping statements like "the foam tires are grippier so the car will be faster" that is a HUGE leap! Stick to what the experiement tells you directly and try to infer intelligently from that. Just as in real life many things are counterintuitive, and as an example, tires that have less adhesion may actually yield faster lap times in certain situations because the car is more "controllable" and less prone to snap spins than high grip counterparts, or another would be that the rubber tires might have less adhesion than foam tired, but on bumpier surfaces are far more compliant (deal with undulations and debris better)... When you make a comparison, alsways make certain it is a "comparision" and not something I see all the time like "X is better..." Better than what? and what do you mean by "better"?
For a practical test, use a large circle and drive around 10 or 20 times for a timed run. But this is much more involved as you would need to have to go out and find suitable locations...
Have fun! and whatever you do, don;t mix science with religion!!!!! *laughing*
Feanor
12-28-2004, 03:30 PM
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RE: Science project : Foam vs Rubber
ORIGINAL: lax195
Ha, well a nice high school project would be to see which one burns faster.
Ha, well a nice high school project would be to see which one burns faster.
Still laughing about this one!!!!! LoL!
