Materials Science C

[hearthstone224]

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!

[Tesel]

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.

[kaziscioly]

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.

[Avogadro]

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.

[Tesel]

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.

[kaziscioly]

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.

[Avogadro]

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.

[Raleway]

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).

[AllenWang314]

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.?

[samlan16]

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.