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chinesesushi wrote: https://wardsci.com/store/catalog/produ ... 470214-370 the compound machine kit from wards has an adjustable fulcrum

Wow, people just buy their compound machines? I think I saw this before at a competition actually... Thanks ChineseSushi

The rules say that the device and any tools must fit inside a box no larger than 100cm x 100cm x 50cm. Is it necessary to give the device inside a box at the impound? Can we give the device as is at the impound. It is difficult to find a box that can be up to this exact or little lower specification. Thanks.

sunvenu wrote:The rules say that the device and any tools must fit inside a box no larger than 100cm x 100cm x 50cm. Is it necessary to give the device inside a box at the impound? Can we give the device as is at the impound. It is difficult to find a box that can be up to this exact or little lower specification. Thanks.

I highly doubt that they'd make us impound it in a box. That's just for size comparisons, like at the airport with baggage restrictions. It has to be able to fit inside the box, but it doesn't need to literally be in a box.

I supervised Simple Machines at an invitational today and I thought I should share some tips before I forget.

Several students used a full meter stick as their lever. However, a brand new meter stick is actually a few mm longer than a meter and thus violates rules 3a, which specifies that your lever arm must be <=1.00 m. I let those kids participate today with a warning but at a regional they would likely be disqualified.

Some students wasted too much time trying to get their device to equilibrium. One team literally used all their time and didn't submit a guess because they spent 3 minutes moving a mass back and forth a few millimeters. If your lever falls to the right, and then falls to the left after moving a mass a few mm, that means your device is very close to equilibrium and also a great device with very little friction. Being 1 mm off will barely affect your calculation, so you should calculate as soon as you find such a spot near equilibrium, and give yourself some more time points.

Bring your own scratch paper to device testing! The supervisor is NOT required to provide something for you to write on. Or feel free to be creative and write on your device or your had or something if you really need to record something.

If your lever isn't balanced before you begin, it will not give you a correct reading.

Your gear ratio/mechanical advantage for a set of gears is # of teeth of OUTPUT/# of teeth INPUT. The answer to my question was 1/2 and more teams put 2 than 1/2.

When calculating IMA for a wheel and axle, you must have the same measurement for both input and output distance - if a problem gives you radius of the axle and circumference of the wheel, you better convert both to either circumference, radius, or diameter.

A wheel and axle has its axle rigidly fixed to the wheel and either the wheel drives the axle or vice versa. Freely rotating wheels are not the same thing as a wheel and axle. Rollerskates are not an example of a wheel and axle. Sliding a Hot Wheels car down a ramp is not using a wheel and axle. A screwdriver is the best everyday example of a wheel and axle.

Are gears considered part of the simple machines though ? Just wondering, since I don't really see where in the rules it specifies this.

Indeed they are!

http://www.soinc.org/node/1222

Also included are belt and pulleys according to the FAQ.

I had a question about the belt and pulley thing. What kind of questions could they possibly ask about belt and pulley? I'm not sure, because it seems like a regular pulley.

chinesesushi wrote:I had a question about the belt and pulley thing. What kind of questions could they possibly ask about belt and pulley? I'm not sure, because it seems like a regular pulley.

Well off the top of my head, a good question would be given the radius of both pulleys, and the rpm of one pulley, what is the rpm of the other?

Also, this would be fun: http://en.wikipedia.org/wiki/Belt_probl ... ey_problem

Ohhh interesting, I was wondering what questions could be asked too. Thank you for those examples

Could I print out pages from a website as long as I site the address in the document?