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Screw Task

Posted: September 3rd, 2018, 7:16 pm
by Unome
See rule 4.b.ix

As tasks go, this one is relatively straightforward. It's been a staple of Div B, since they focus on Simple Machines.

Re: Screw Task

Posted: September 7th, 2018, 8:18 am
by Wabbit
Do we think that the screw must be in contact with the object it is moving for the whole time? For example, if the screw was moved horizontally only about one centimeter, but made contact with a ball, hitting it and causing it to roll for an additional one or two centimeters, would that satisfy the rules?

Re: Screw Task

Posted: September 7th, 2018, 8:23 am
by nicholasmaurer
Do we think that the screw must be in contact with the object it is moving for the whole time? For example, if the screw was moved horizontally only about one centimeter, but made contact with a ball, hitting it and causing it to roll for an additional one or two centimeters, would that satisfy the rules?
The descriptions states that the screw must achieve two tasks: operating as a screw AND moving an object 2cm. I would argue if you bump a ball and simply allow it to roll, gravity is moving the ball for most of that 2cm, not the screw.

Re: Screw Task

Posted: September 7th, 2018, 8:28 am
by Wabbit
Do we think that the screw must be in contact with the object it is moving for the whole time? For example, if the screw was moved horizontally only about one centimeter, but made contact with a ball, hitting it and causing it to roll for an additional one or two centimeters, would that satisfy the rules?
The descriptions states that the screw must achieve two tasks: operating as a screw AND moving an object 2cm. I would argue if you bump a ball and simply allow it to roll, gravity is moving the ball for most of that 2cm, not the screw.
I wasn't thinking about using gravity or a ramp. If a screw with wide enough threads is turned fast enough it could hit a small ball and get it to roll across a flat surface. In this case, the screw would be providing all of the energy that the ball needs to move, but the screw would not need to move the full 2 cm itself.

Re: Screw Task

Posted: September 7th, 2018, 8:34 am
by nicholasmaurer
Do we think that the screw must be in contact with the object it is moving for the whole time? For example, if the screw was moved horizontally only about one centimeter, but made contact with a ball, hitting it and causing it to roll for an additional one or two centimeters, would that satisfy the rules?
The descriptions states that the screw must achieve two tasks: operating as a screw AND moving an object 2cm. I would argue if you bump a ball and simply allow it to roll, gravity is moving the ball for most of that 2cm, not the screw.
I wasn't thinking about using gravity or a ramp. If a screw with wide enough threads is turned fast enough it could hit a small ball and get it to roll across a flat surface. In this case, the screw would be providing all of the energy that the ball needs to move, but the screw would not need to move the full 2 cm itself.
Interesting point... As long as the screw undergoes two full rotations, imparts the momentum by acting as a screw, and provides all of the energy to move the object 2cm I think that should be fine.

Re: Screw Task

Posted: September 9th, 2018, 7:31 am
by ET2020
What does "Use gravity to clearly rotate a screw" mean? Would dropping a weight that is attached by string to a screw count as using gravity, or does the screw have to somehow turn due simply to its own weight?

Re: Screw Task

Posted: September 9th, 2018, 7:51 am
by nicholasmaurer
What does "Use gravity to clearly rotate a screw" mean? Would dropping a weight that is attached by string to a screw count as using gravity, or does the screw have to somehow turn due simply to its own weight?
I would interpret this as requiring that all of the kinetic energy required to turn the screw must come directly or indirectly from gravitational potential energy. It does not say the screw must provide said potential energy.

Re: Screw Task

Posted: September 14th, 2018, 9:30 am
by LostInTheSauce
What exactly does it mean to operate as a screw? Does it literally have to screw into something, or as long as it rotates, it's fine? Also does the screw itself have to move linearly, or can the screw's rotation cause something that is perpendicular to the screw to move linearly?

Sorry a lot of questions here :D

Re: Screw Task

Posted: September 14th, 2018, 10:18 am
by nicholasmaurer
What exactly does it mean to operate as a screw? Does it literally have to screw into something, or as long as it rotates, it's fine? Also does the screw itself have to move linearly, or can the screw's rotation cause something that is perpendicular to the screw to move linearly?

Sorry a lot of questions here :D
I would rely on the simple machine definition of a screw, which incidentally is included directly in the text of 4.b.ix: "converting rotational force into linear force." That does not require it to screw into a solid substrate.

Re: Screw Task

Posted: November 24th, 2018, 12:27 pm
by honorstoise
So I have a golf ball hot glued to the screw in the bottom so that it goes down 2 centimeters and hits a lever to initiate the next action. Would this count as a conversion of rotational force into linear force?