<p>I have to do a project at school that involves making a slow roller car using a yo-yo. This car has to roll the longest time down a meterstick ramp. Can anyone assist me with any ideas?</p>
<p>put the most weight at the front? Lube the yo yo… Light weight mateirals, put special speed boosting gel on the wheels…
Whatever…</p>
<p>aha it isn’t a yo-yo, but its supposed to be like one eh? anyway my suggestion is fins and lots of them, like on a fan or a pinwheel, and keep the weight as low as possible also makes the axle that rolls on the meter stick as small as possible. the more revolutions, the more time</p>
<p>Wait… so are you trying to make the car move quickly or slowly?</p>
<p>the car is suppose to move slowly</p>
<p>If it’s supposed to move slowly, a large radius with most of the mass concentrated at the rim of the wheel will provide the most rotational inertia. Generally, the more mass you pack the farther out, the slower it will rotate and thus move.</p>
<p>It’s the same principal as a skater pulling in their arms to speed up their rotation, or holding out your arms while spinning on a chair to slow down rotation. The farther out you can get more mass, the slower it will go.</p>
<p>Anzanar, that might work, but you need to realize, it’ll be slow to accelerate, but it’ll also be harder to slow it down with fins and air resistance. So, its a bit of a trade off. Since air resistance increases non linearly with more velocity (I think its squared, or an exponential equation of some sort) I think having the mass concentrated at the center would be better, because although it would accelerate faster, it would be easier to slow down more quickly, resulting in a lower terminal velocity. Anyway, I say you shouldn’t try to concentrate the mass at the inside or on the rim, since if you’re building lots of fins, since that is what will slow down your “slow roller” the most.</p>
<p>Mass around the riim will definitively slow it down, as will a lead cart. Pack enogh mass but not too much.</p>
<p>Motion problems with air resistance are differential equation problems:
eg.: (-kv is the force that slows you down)
-kv = m(dv/dt)
Solving it for v will give you:
v = v0 e^(-kt/m)</p>
<p>Air resistance isn’t the big factor here. Usually, when designing these “competitions” in physics, the main point is not to emphasize friction/air resistance but to emphasize some physical property of matter. Unless you use paper-light material to create the car (at which level I admit air resistance means more), the best design is going to involve taking rotational inertia into factor.</p>
<p>If you car make the car out of very light materials, then go for light with fins.</p>
<p>Otherwise, lots of mass concentrated at the rims of the wheels will serve you best.</p>
<p>i have to agree with mass on the rims</p>
<p>you could make a rubber box and put the yoyo inside; that would never move!</p>