Forensics C

[meggers1221]

can someone tell me which powders are NaOH reactive and which are not?? thanks so much!!!!!!!!!!!!!!!!!

[meggers1221]

Allright, I'm officially cramming, can someone tell me all of the plastics, and the densities and burning if possible! sorry guys!

[personasaurus rex]

Anyone who went to Athens yesterday know what the two plastics were? I was pretty certain about my answers but they turned out to be wrong and we didn't receive answer keys at the end of the competition...

I think the answer keys were digital for Forensics, check the USB?

Wait what USB? I thought the only digital things we got were two CDs for Disease and MagLev?

[sciencegirl23]

The coaches have a USB drive, I saw it, I dont know what's in it though. It was in the packet of tests.

[willowmist]

The sugar I remember smoked pretty obviously when I took it out of the flame; salt turned the blue burner flame to orange (anything with sodium will turn it orange, actually).

I think our chromatography was just messed up...they didn't give us a beaker right away, so we resorted to a test tube, which may have screwed up our answers. I saw two main inks, a pink-ish one and one that was sort of olive-coloured?

The angles I remember I got were 38 and somewhere around 20 (haven't gotten our tests from our coach yet, so I dunno if any of my answers are right). You might have rounded the measurements or something? I was really OCD about it. Point of origin the way I did it was since I know the impact angle and the distance from the bloodstain to the convergence point, I did tan(38) = (height of origin point)/(distance from convergence point) and rearranged it to solve for the height.

Ah, cat hair was right? Good. I remember that silk matched Hermione, because my partner was relatively sure it was wool, which matched none of the suspects - silk burns in a similar way.

Ack, I don't remember the sugar smoking... D:

For chromatography, the inks we had were this dark purpleish/gray one, a yellow one, and a pink one. On ours, there was also a mix between the gray ink and pink, which I'm not sure if it was another ink, or just the purple/gray ink got tinted somehow and it showed up weird? Didn't see an olive-colored ink though.

Ah, well, at least I was... somewhat... close? I don't think I rounded it by that much, if at all, but that's the most probable possibility since our angles were only off by a few degrees. And woah, for origin height... Ahah, I get it now. If only I'd thought of that too.

Oh, so it was silk? And silk looks similar to linen and the synthetic fibers too, I think, so we could have mixed it up.

[bugsrcool]

For those of you at Conestoga, I wrote the test. The answer key I gave your coach was slightly wrong. I used the corrected one to grade with.
1. The glucose was sucrose (packed wrong one). Only showed that powder from donut was on his robe, did not change implicating anyone else.
2. The actual height for the point of origin was around 8 feet (to show a struggle and that the wound had to be on the hand above head).
3. I should have mentioned that none of the plastics burned with copper (I just said that burn tests were not necessary.)

Overall, I had fun writing the story line. Remember when you write your analysis to include why each piece of evidence does not implicate as well as implicates the suspect. Being not guilty is just as important as being guilty. Good luck at your regionals (PA teams) and states (NJ teams).

[meggers1221]

okay at the event, will they give us the different densities that we need to float the plastics in?

[AlphaTauri]

2. The actual height for the point of origin was around 8 feet (to show a struggle and that the wound had to be on the hand above head).

Not to pick a fight with the test writer or anything, but I'm curious about something: isn't the point of origin "less than or equal to 8 ft up" since spattered blood generally follows a parabolic trajectory, not a linear one? I thought I read somewhere that calculating the height of the point of origin with trig only gave a maximum height, not a definitive height.

Very well-written test, btw. My partner and I loved the plot, even if we weren't really that fond of the test itself (since we were really pressed for time due to the length and our relative inexperience with the event).

[salcedam]

okay at the event, will they give us the different densities that we need to float the plastics in?

It depends on the writer of the test and what materials are available. Sometimes proctors will give various liquids in which to test densities, sometimes they will just give flame tests or something. You just have to be ready for anything when it comes to Forensics tests. The Forensics test that I had recently taken at the Belvidere invite didn't have any flame testing or any sort of tests at all. I didn't have to use my bin except for a ruler and magnifying glass because all the proctor had us do was match the powders by looking at them and writing down observations. A lot of people had complaints about that test, but bad tests happen. It was basically a free-for-all test where you didn't know definitively if you did well or not because it was all based on how good your observations were.

[NinjaChicken]

How about soil analysis? Anyone have a site I can go to for that?