Question Roundup

I've mostly been answering questions in the comments, rather than doing the full posts I did before, but I thought I'd collect some of the ones I've answered recently for anyone who doesn't check those.  I'm also doing this so I can better answer the question I got earlier today, which I'll start with:

Chris asked about this post, "hah! I want to see the calculation for your whole body quantum tunneling partway through a wall"
I think that one actually came from an example problem in the quantum mechanics text I used.  I just adapted it for a whole person, instead of whatever small particle it was actually about.  The main calculation I did for the shirt was for the raptor.  I decided to have it condense out of air molecules that collide to form the necessary proteins and other biological chemicals.  I collected all the info I needed in a big spreadsheet, which I still have, so I can show you a couple bits of it.
Here's the chemical makeup of the raptor:

Ingredients	Fraction by Mass	H	O	C	K	Na
Water	0.71	2	1	0	0	0
Fat	0.116	98	6	55	0	0
Cholesterol	0.00075	46	1	27	0	0
K	0.0019	0	0	0	1	0
Na	0.00154	0	0	0	0	1
Proteins	0.232	5	2	2	0	0

And here are the bits of information I progressively calculated:

Meat Density	1042 kg/m^3
Raptor Mass	15 kg
Raptor Volume	14.4 liters
Air Density	1.2 kg/m^3
Air Volume	12500 liters
Change in Entropy	-28566 J/K
Probability of Compression	1 in 10^(10^27)
Area of Swat	3.6 km^2
Area of Globe	510072000 km^2
Fraction of Globe	10^-8
Energy to Split N	2863.417 keV
Energy to Split O	−4737.0014 keV
Energy to Split C	0
Speed to Split N	6282376 m/s
Probability of Finding Speed	1 in 10^(10^54)
Moles of N Needed	1253
Particles of N Needed	10^27
Probability of Finding Speed Repeatedly	1 in 10^(10^81)

It was a fun thing to figure out, for a physics geek like me.

Now on to the old questions...

Nate asked about this post, "How about maximum pressure? It might be cheapest to manufacture the container out of a single material, rather than making some parts of it stronger than other"
I'm not an engineer, so I'm not too clear on the details of material strength, but if you were looking for smallest maximum pressure, you'd simply want the shortest container. In this case, that would be the rectangle, but I assume that's a bad idea, based on the fact that you don't see any on the road.

Kevin asked about the same post, "I was watching a passing train the other day, and I noticed that the "cylindrical" cars were actually slightly pinched toward the middle (of smaller radius about the same axis). Got any ideas why that might be a good design?"
Off the top of my head, my guess would be for draining it. With a "flat" bottom, defects could trap the liquid, but by intentionally sloping it, that's much less likely.

Thanks for the questions, guys!  Please keep them coming, or I might get lazy...