Physics Lab B/C

[Melkor6000]

I built a fan for the first time today out of a 2 liter bottle. It has3 rounded, curved blades attached to the disc with some balsa wood and super glue. I tried testing it but after reaching a certain speed, the disc would pop off of the cd rotor.

any advice on how to improve the design? The blades are about 2.5 inches wide. Should I make them thinner and taper them?

Read the chapter in an AP Physics textbook about rotational motion and rotational inertia. That will best explain your question about tapering. Also consult the websites referenced on the rules for information about pitch of the blades. Both of these topics are useful to know, and you will understand better after researching some on your own rather than people trying to explain in this forum.

[overdramatic]

Does anybody have a better idea on what to study at this point? We had our regionals not even a week ago and the test was pretty good. It did have a few thermodynamic questions, and a LOT of general Physics questions. Very little on actual alternative energy, though. Thankfully there were no random statistics questions. And there was a question or two on the wind power equations. Now, I'm attempting to study for NY States, but I feel like the test could ask anything on Physics at this point. What have you guys seen on your tests?

[JStark]

@ an invitational, i took a test where there was mostly power/energy questions

my regionals had several MC questions that were really general about alternative energy
and then it had quite a bit of short answer that were mostly power/efficiency problems

i posted an 1800 combined rating on my fan, won regionals .. everybody else had sub-500 fans. im still looking to get 2000+ but ive gotten no where in two weeks of work, blah

i think 1800 will be very average at states :\

[wyu1229]

can anyone add a physics lab exam on the test exchange? The one that's on there already from last year isn't challenging enough

[Melkor6000]

can anyone add a physics lab exam on the test exchange? The one that's on there already from last year isn't challenging enough

No one has gotten back to my coaches about scrimmage or regionals tests, so I can't help there.

Does anybody have a better idea on what to study at this point? We had our regionals not even a week ago and the test was pretty good. It did have a few thermodynamic questions, and a LOT of general Physics questions. Very little on actual alternative energy, though. Thankfully there were no random statistics questions. And there was a question or two on the wind power equations. Now, I'm attempting to study for NY States, but I feel like the test could ask anything on Physics at this point. What have you guys seen on your tests?

The two tests I have taken (scrimmage and regionals) have been very different, and I expect something different yet at States.

Here is what the test had in common:
Nothing about cycles, but lots of heat transfer, and trivia--which is cheap, if you ask me.

[sparky007]

Any suggestions for low-speed blades?

Right now I'm getting .8V on our set-up.

[an_olympian]

How specific were the questions you all were asked on your tests, and how much of the "suggested" material did they cover? At our invitational competition, we had almost no equation-type questions; they were all mostly facts or explanations, but some of the questions were very, very specific/obscure and some were very basic and general.

Also, how long were your tests? Ours was ridiculously short, in my opinion (1 page front/back only).

//edit

Any suggestions for low-speed blades?

Right now I'm getting .8V on our set-up.

.8V on low? I think you should be giving us suggestions ;_;

[jiayobaka]

Proctor tested and said that the speed was really good, but was disqualified because I didn't know we had to impound. :[

[smarticle13]

is physics lab for division c the same thing as physical science lab for division B?
-just curious

[AlphaTauri]

Yup, it's basically the same thing, except that for C you can only impound 1 blade assembly (instead of 2) and there's more stuff you have to study.