Quote:
Originally Posted by CraigD
The design sketched in the attached image is nothing but 2 wheels of about 30 cm diameter joined by an axle, a drive string connected to the weight and wrapped around the axle, and a support string looped loosely around the axle and attached to the weight to prevent it from descending more than the allowed 10 cm and touching the ground. The axle has a diameter less than 1/100th that of a wheel, so it should roll more than 10 m under power, coasting perhaps a bit further.
[ATTACH]http://hypography.com/forums/science-projects-and-homework/19557-weight-powered-car-6.html[/ATTACH]
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I can't even figure out how to get the attachment to display (
turtle down!), but nonetheless something about this particular elegant design keeps nagging me. With 30cm wheels, the radius is 15cm, and subtracting the 10cm drop we have but 5cm left. Allowing say a 1mm clearance between ground and fully fallen weight, we have only a 4.9cm clearance between the top of the weight and the axle when the weight is fully up. The upshot is that these exact design dimensions constrain the physical dimensions of the 1kg weight to a degrree that a "standard" lab 1kg weight may not fit.
The thinner the weight in its vertical dimension, the smaller diameter wheels one can use down to a limit of maybe 10.2cm (20.4cm diameter with a 1mm clearance & 1mm thick weight), but making the weight thin, one must either use a longer axle and separate the wheels wider, or have the weight stick out front & back, or both. Given these new constraints, what might make the ideal situation now for a 2-wheel 1kg weight-powered vehicle? (Shall we specify a
lead weight for arguments sake? Gold? )
PS just realized no reason the weight could not have a slot for the axle & string to pass through & actually start & remain partially above the level of the axle at the end of the fall.
