## Materials Science C

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### Re: Materials Science C

parasaurolophus wrote:
parasaurolophus wrote:Hey guys, have you encountered any instances in which you had to calculate creep rate? I am finding some more complex equations that all involve calculus that are above the level usually included in Science Olympiad.

Yes, several times, though generally using given data points. Plot it to find the linear region (secondary creep), and your standard delta y over delta x usually suffices. I have yet to see a scenario involving calculus.

Thank you so much! So do Materials Scientists generally not care about the primary and tertiary creep? Or rather, for Science Olympiad purposes

For Science Olympiad purposes I haven't been too concerned about it. I'm sure it's more important if you're actually an engineer.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

hearthstone224
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### Re: Materials Science C

Question on closed packed planes coming at you guys if you don't mind. This comes straight off a practice test and is as follows:

Give the Miller indices of a family of close packed planes in copper. Use the conventional notation indicating a family of planes.

1. What is a close packed plane?
2. Where is this plane (isn't it just from 0,0,0 to 1,1,1 the plane that is formed there?)
3. Why is the answer {1,1,1}? How do you just know that?

Ok Thanks for the help.
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

hearthstone224
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### Re: Materials Science C

So I've looked it up and apparently there was something called slip all along, with specific planes that are easier to slip (which I think basically means to break/plastically deform easier on) on and these planes are along the close packed planes. {1,1,1} seemed to be the first one they said. Should I memorize these planes? There really isn't a way to "derive" them, is there? Like you just have to know them?
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

younessnb
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### Crystal Structure

Hello everyone! I'm hoping to see if anyone can help me figure out how to determine the crystal structure that will be formed or a given material There have been questions on the practice tests that ask us to figure out the crystal structure of materials such as sodium chloride and I am not too sure how to figure that out without memorizing the structures of the materials. Thank you so much for your time!

hearthstone224
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### Re: Crystal Structure

younessnb wrote:Hello everyone! I'm hoping to see if anyone can help me figure out how to determine the crystal structure that will be formed or a given material There have been questions on the practice tests that ask us to figure out the crystal structure of materials such as sodium chloride and I am not too sure how to figure that out without memorizing the structures of the materials. Thank you so much for your time!

Something that might help would be the wiki, which kind of helps to explain the 6:6 ratio coordination between Na and Cl. Basically it means you have sodium atoms surrounded with 6 other atoms.

I'm really not quite sure though, I think there is something related with the atomic radii, and then you actually take a ratio between them and then you can figure out how it is coordinated... Maybe someone else can help. Hope this helps, though.
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

hearthstone224
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### Re: Materials Science C

I'd just like to thank everyone for their help. Freshman season officially over.

Got SECOND at regionals out of 12 teams for Materials Science (Only team that beat us was Stevenson which is a nationally ranked team) and so I'm very proud. I'll still be on the forums once in a while but probably won't be too dedicated anymore..

Just like to say thanks to everyone, and best of luck to all you guys out there! I really made myself a competitor and it showed today at the regional. Thanks and have a good one!
End of freshman season. Good luck to everyone! No state for us, but nevertheless great season. Regional was out of 12 teams. (CLC)

Mat Sci-> Second at regionals
RSensing -> First at regionals
Towers-> Third at regionals.

Tesel
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### Re: Materials Science C

Just had my regionals test this weekend, got 1st place!
Thanks for everyone who helped me figure out atomic packing, that section may have been the difference.
I was just boggled by one question... it showed a graph about reflection angle and intensity, and asked the spacing between certain atomic planes? If anyone understands what this is, I am very confused, and I'm not even sure if that's within the limits of the event.
MI Mission Possible State Champions!
2018: Portage/Haslett/Allendale/GVSU/MSU
Chem: 3/4/2/1/8
Hover: 1/2/1/1/6
MatSci: 2/1/2/1/3
Mission: 5/3/1/2/1

kaziscioly
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### Re: Materials Science C

Does anyone have any experience/advice about making cubic crystal models? We had to do something like this at our regional where we were given toothpicks, styrofoam balls, and beads to make a model of an FCC crystal, and that was a frustrating experience.

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### Re: Materials Science C

kaziscioly wrote:Does anyone have any experience/advice about making cubic crystal models? We had to do something like this at our regional where we were given toothpicks, styrofoam balls, and beads to make a model of an FCC crystal, and that was a frustrating experience.

Yeah, I did exactly the same thing at Stoga and it made me want to rip my hair out. My best advice is to just 100% impale the things and get as many connections going as you can. If you're limited to only getting a certain number of styrofoam balls/toothpicks (like I was at Stoga) you need to be careful about how you impale the things, making sure you leave enough room to attach the other stuff to it. If you're not, I'd say to just go to town until you put together a working model.

tl;dr models are a crapshoot based on quality and quantity of materials given, from my experience.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

Tesel
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### Re: Materials Science C

kaziscioly wrote:Does anyone have any experience/advice about making cubic crystal models? We had to do something like this at our regional where we were given toothpicks, styrofoam balls, and beads to make a model of an FCC crystal, and that was a frustrating experience.

Yeah, I did exactly the same thing at Stoga and it made me want to rip my hair out. My best advice is to just 100% impale the things and get as many connections going as you can. If you're limited to only getting a certain number of styrofoam balls/toothpicks (like I was at Stoga) you need to be careful about how you impale the things, making sure you leave enough room to attach the other stuff to it. If you're not, I'd say to just go to town until you put together a working model.

tl;dr models are a crapshoot based on quality and quantity of materials given, from my experience.

Approximately how many of each were you given? I could see this being a good lab, but if materials were limited, that wouldn't really be in the spirit of the event.
MI Mission Possible State Champions!
2018: Portage/Haslett/Allendale/GVSU/MSU
Chem: 3/4/2/1/8
Hover: 1/2/1/1/6
MatSci: 2/1/2/1/3
Mission: 5/3/1/2/1

kaziscioly
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### Re: Materials Science C

Tesel wrote:
kaziscioly wrote:Does anyone have any experience/advice about making cubic crystal models? We had to do something like this at our regional where we were given toothpicks, styrofoam balls, and beads to make a model of an FCC crystal, and that was a frustrating experience.

Yeah, I did exactly the same thing at Stoga and it made me want to rip my hair out. My best advice is to just 100% impale the things and get as many connections going as you can. If you're limited to only getting a certain number of styrofoam balls/toothpicks (like I was at Stoga) you need to be careful about how you impale the things, making sure you leave enough room to attach the other stuff to it. If you're not, I'd say to just go to town until you put together a working model.

tl;dr models are a crapshoot based on quality and quantity of materials given, from my experience.

Approximately how many of each were you given? I could see this being a good lab, but if materials were limited, that wouldn't really be in the spirit of the event.

I don't recall the numbers from when I did this, but we had an excess of styrofoam balls and not enough beads to make the structure. The toothpicks were also too fat to slide the beads on to, so we basically just made a cube out of styrofoam balls and shoved whatever couple of beads we had on to the very tips of the toothpicks.

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### Re: Materials Science C

I don't recall exact numbers, but it was approximately 16 styrofoam balls and the toothpicks were (relatively) unlimited. There were only about two beads per group though, which we were told to put in "about the right spot". So... yeah.
Lower Merion 2017
Subtitled: Revenge of the Non-Harriton

Placement Record:

Code: Islip | Conestoga | Tiger | Regionals | States
Out of: 61 | 42 | 36 | 37 | 36

Chemistry Lab: 9 | - | - | 4 | 4
Astronomy: 14 | - | 5 | 10 | 3
Material Science: 12 | 19 | 9 | 5 | 9
Optics: 14 | 7 | 3 | 4 | 2

Raleway
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### Re: Materials Science C

At one invitational (SOUP), the "lab" or w/e you can call it was identifying the models. They were wood/ball models. I feel that it would be your best bet to imagine (or draw out) what it would be like with only whole balls and then connect them. In this way you might not need to make a diagonal stick (SOUP had all 90 degree sticks and you had to identify own cubic cell).
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AllenWang314
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### Re: Materials Science C

What does it mean when we say, "kevlar is stronger than spider's silk"? Does it refer to ultimate tensile strength, yield strength, or young's modulus, etc.?
Without geometry, life would be pointless.

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samlan16
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### Re: Materials Science C

AllenWang314 wrote:What does it mean when we say, "kevlar is stronger than spider's silk"? Does it refer to ultimate tensile strength, yield strength, or young's modulus, etc.?

According to this paper (not posting the chart here due to copyright stuff; scroll down to p. 6), both the compressive and Young's moduli are greater for Kevlar. UTS is a bit subjective in this case because the cross-sectional areas of the fibers were different.
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