Physical Science Lab

[orlandoscience]

guys, do you have any invitational questions for physical science that you can share?


http://www.scifl.blogspot.com

[A Tang]

Watts measure a rate of energy transfer. Volts measure energy per unit charge. So you can't turn Volts into watts, because they are completely different things.

I see my ignorance.

I've been getting 900 millivolts.

[Pleiades]

I've been getting 900 millivolts.

is that for the combined low+high speed?

[A Tang]

Assuming I know what that is, it's my high speed.

[bobothesciencezombie]

Hey, I haven't had my regional yet but I've been successful so far using pieces cut from the warped edges of a shampoo bottle. Also, I keep the turbine as close as possible to the fan.

[Uncle Fester]

Something to be aware of:

CD motors come in 3, 5 and 12 volt versions. Your output voltage WILL vary depending on what motor the event sup uses! However, it won't affect your performance compared to everyone else, as you ALL will be using the same motor. It's ratio thing.

[Uncle Fester]

ALSO, Some electrical theory for you:

Power = Volts * amps.
and
Power = Volts ^2 (squared) / resistance of load.

Since you're using a DMM to measure your voltage output, and there's no additional load, the DMM's multi-MegaOhm impedance is the load. Divide by near-infiniuty, and you have nil (approaching zero) load slowing the motor.

This means that SPEED is the sole determiner of your output. Most windmills you see are designed to drive a hefty load, and are built as such, and that's not the contest criteria here.

Best ones I saw (so far) were all small, two and three blade devices, all well-balanced.

[Loser]

How much of the score does the blade testing account for and how much does the test account for in the total score?

[icyfire]

Regionals for us are coming close and though we have a pretty good blade we don't know as much on the test portion of the event. Any suggestions for specific ideas we should study? Thanks.

[haven chuck]

Try to get the CONCEPTS, not just specific facts. Dumbed down versions of the technology (like websites meant for kids) are actually good for understanding concepts, and then specific facts can be in the binder