0135: "Substitute"

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0135: "Substitute"

Postby xkcd » Mon Jul 31, 2006 7:12 am UTC

I think I'm gonna start the thread on the comic this time!

Today's comic features Kira, who you may have seen around on the forum, and who will probably not let me near any of her math classes at this point.

Anyway, velociraptors are horrifying. What is up with the lack of any good dinosaur movies lately?

I was just launching into a spiel listing everything that was done wrong with Jurassic Park III, which made The Lost World actually look good. But I think it's not really necessary. I'm just gonna keep sitting here and waiting for a decent movie with raptors so I can start eyeing the bushes as I walk to my car every morning again.

In other dromeosaurid-related news, I just brought back a stack of books from my house, and while I didn't find the Achewood collection I was looking for, I did coincidentally stumble on my old copy of Raptor Red moments after today's comic went up. I think the world is trying to prepare me for something.

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Postby Jack Saladin » Mon Jul 31, 2006 7:36 am UTC

The funniest bit was the alt text.

But yeah, while what I've seen of the script for JPIV looks OK for a bizzare sci-fi fest, doesn't look like a great dino movie. There needs to be something else.

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Postby kira » Mon Jul 31, 2006 10:26 am UTC

I'm famous!

Does anyone know if it's legal to tell students that they'll get eaten by a velociraptor if they don't do their homework? I don't think I'd be necessarily lying... although they'd get eaten by a velociraptor if they did their homework too.

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Postby Jack Saladin » Mon Jul 31, 2006 10:32 am UTC

Don't tell them- just let them happen upon a bunch of gruesome diagrams showing exactly what velociraptors do to naughty children.




Cause, y'know, velociraptors are into education and stuff.

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Postby Belial » Mon Jul 31, 2006 11:55 am UTC

I did coincidentally stumble on my old copy of Raptor Red moments after today's comic went up.


Can I borrow that sometime soon? I lost my copy.

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Postby Shoofle » Mon Jul 31, 2006 1:38 pm UTC

The worst thing ever is when you are talking about Utahraptors and referring to them as Velociraptors and someone is like "Velociraptors were pretty small! You mean Utahraptors!" because the point is that velociraptor is a much more common name and everyone is much more likely to understand you and also velociraptor sounds way cooler.

I think that if I were making a list of the best movie moments of all time, the part where Dr. Grant mock-disembowels the kid, using the velociraptor claw.

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Postby Matt » Mon Jul 31, 2006 9:56 pm UTC

Tomorrow: THE FLOOR PLAN
Hi. I'm from Massachusetts.

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Postby zombiereagan » Mon Jul 31, 2006 11:36 pm UTC

beyond the need for a good dinosaur movie is the need for a sweet dinosaur killing video game. The first two Dino Hunter's were a good time but the 3rd one was terrible and i need my raptor hunting fix. Or rather i want to test my wits against a pack of intelligent raptors rather than just blast them with my autoaim as they appear on screen.


Just imagine Metal gear solid 3


but with raptors.
whatever doesn't kill you only serves to horribly maim you.Image

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Postby xkcd » Tue Aug 01, 2006 12:11 am UTC

zombiereagan wrote:beyond the need for a good dinosaur movie is the need for a sweet dinosaur killing video game. The first two Dino Hunter's were a good time but the 3rd one was terrible and i need my raptor hunting fix. Or rather i want to test my wits against a pack of intelligent raptors rather than just blast them with my autoaim as they appear on screen.

I've always wanted the game where you play as the dinosaurs, but only if done well. Like, where they do a good job of making you feel like you're actually a dinosaur, and not just watching one move in response to your commands. Like Oni was with martial arts, when compared to the six minutes of BloodRayne I played..

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Postby Shoofle » Tue Aug 01, 2006 2:06 am UTC

I need that floor plan - I gotta get my grades up for the midterm.

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Postby Guest » Tue Aug 01, 2006 5:04 am UTC

xkcd wrote:I've always wanted the game where you play as the dinosaurs, but only if done well. Like, where they do a good job of making you feel like you're actually a dinosaur, and not just watching one move in response to your commands. Like Oni was with martial arts, when compared to the six minutes of BloodRayne I played..



Dude you actually played Oni too?! Right on.


I hear the bloodrayne thing to...i got a couple feet and then was done with that.

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Postby Jack Saladin » Tue Aug 01, 2006 5:12 am UTC

zombiereagan wrote:beyond the need for a good dinosaur movie is the need for a sweet dinosaur killing video game. The first two Dino Hunter's were a good time but the 3rd one was terrible and i need my raptor hunting fix. Or rather i want to test my wits against a pack of intelligent raptors rather than just blast them with my autoaim as they appear on screen.


Just imagine Metal gear solid 3


but with raptors.


Holy shit yes. I loved Dino Crisis 1 and 2, 2 especially, space-bullshit 3 was crap.

CQCing a raptor = best thing in the world.

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Postby Guest » Wed Aug 02, 2006 3:04 pm UTC

So I worked out #1, but I am a lowly second-semester calculus student and have no clue how to do #2 but I feel the need to understand it. So I figured someone here might be able to help, please? Thanks in advance.

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Postby ArbiterOne » Thu Aug 03, 2006 3:08 am UTC

Tell me if this is right. I tried to 'intuit' my way through this.
Since the system is symmetrical, there are two correct angles.
The angle you need to run is between the wounded raptor and a non-wounded raptor (either side). Now, my guess would be that it would be:

Code: Select all

angle between raptors * ( speed of wounded raptor / (speed of wounded raptor + speed of non-wounded raptor) )
120 * ( 10 / (10 + 25) )
~= 34.285 degrees
or 274.285 degrees

... is there actually a canonical answer to this?
POST THE MAP so we can do question 3!

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Postby twenty10 » Thu Aug 03, 2006 3:51 am UTC

I thought about #2 for a bit and remembered how much I respect the power of calculus.

you're right about there being two correct angles, provided the two raptors at the lower ends of the triangle are identical in all regards save initial data. it really depends on how much detail you want to go into. does raptor b react faster than raptor c? maybe raptor c can pivot quicker than raptor b.

it's all pointless musing though, as we all know that raptors would slowly circle you in a fibonacii spiral where, in the limit as t approaches mutilation, the rate at which the distance between you and velociraptory-death would increase faster than the rate at which you're panicing, due to the fact that one raptor would pounce at you whilst the other two run in from other sides, ensuring your death quicker than you can fully comprehend the calculated oblivion which you face. :D
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Postby paige42 » Thu Aug 03, 2006 4:14 am UTC

Assuming the wounded raptor can still accelerate at 4 m/s^2, the raptors are all moving at the same speed for the first 2.5 seconds (but at t=2.5 they reach 10 m/s, and the wounded one stops accelerating).

So, I would begin running at an angle of 60 degrees away from the wounded one.

I'm too lazy to work out what happens after t=2.5, but do I at least get partial credit? :D
Poets say science takes away from the beauty of the stars — mere globs of gas atoms. Nothing is 'mere'. I too can see the stars on a desert night, and feel them. But do I see less or more?
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Postby Vyathx » Thu Aug 03, 2006 7:43 am UTC

I'm assuming from the first question that by failing to mention the acceleration rate of said human, it means he has an instant acceleration reaching the top speed of 6m/s.

Now, since it's an equilateral triangle, and I am led to believe that the raptors take linear paths on their way to the victim, in all likelihood the non injured ones will reach the center at the same time. Now, in order to maximze the human's chances of staying alive, rather than choosing an angle between the injured and non-injured raptor, the best thing would be to choose an angle between the non-injured raptors. You see, by waiting until the very last possible moment, then acclerating to 6m/sec, the the two raptors collide upon reaching the center and thus their velocity returns to 0. The injured raptor, at this point has a velocity of 10 m/sec, but the distance between him and the center of the triangle is less then 10 meters.
This leaves him with 3 options:
The good ones (for the human)-
1. He collides with the other two raptors. This obviously gives more time for the human runner.
2. He takes a route around the two raptors, breaking free of the linear path. By extending the path he distances himself from the human, giving him even more precious time.

The bad one -
3. He maintains his straight path and jumps over the other raptors. Unlikely, since the raptor is injured, but if that's the case it gives the human even less time seeing as how choose to wait instead of running. The distance between the injured raptor and the two raptors is less than 10 meters, and the human manages to reach only 6 meters from the center. This means that in less than 2 seconds the injured raptor will get to him.
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Postby Belial » Thu Aug 03, 2006 7:53 am UTC

This of course presumes that the raptors will act first.

If they behave like any other semi-intelligent predator I've ever seen, they will approach slowly, at a walking pace, until they are either within disemboweling-distance, or the prey bolts, and *then* choose a path to take the prey down. No top speed collision in the center of the triangle, just high speed pursuit out of it. .

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Postby ArbiterOne » Thu Aug 03, 2006 1:01 pm UTC

And assuming that a "Jurassic Park III: The Raptors Are Intelligent ZOMG!!!111one" situation doesn't occur, and therefore they don't have, say, shotguns. Or precision laser-guided missiles.
Image

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Postby DaveFP » Thu Aug 03, 2006 2:03 pm UTC

I have another theory, which may be completely wrong. It really depends on whether you can get past one of the 'lines' of the triangle before a raptor tears a hole in you.

Standing at the centre of the triangle, you are equidistant from each raptor. suppose for a second that each raptor is healthy. Because you're so slow compared to them, you can't escape. Whichever direction you do run will actually bring you closer to a raptor, hastening your death. Therefore I would conclude that the best policy here would be to stay still.

With one wounded raptor, things change a little. You still can't escape, but now the to bottom raptors will reach you first. In order to survive longest, you need to stand at the point where all three will reach you at once (or at least one fast and the slow one). Now without sitting down and calculating the whole thing, the shortest route to that point is straight up.
Image

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Postby zombiereagan » Thu Aug 03, 2006 8:37 pm UTC

dig a tunnel with your bare hands
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Postby RealGrouchy » Fri Aug 04, 2006 4:55 pm UTC

Belial's suggestion aside, are we to assume that they stay going in a straight line toward the centre, or are we to assume that they change their trajectory as the pitiful human (c/o Morbo) changes position?

The real reason that I wanted to post was because I read this one after "science fair", and the top-view diagram of the 'raptors reminded me of the diagram from "science fair".

Also, ArbiterOne, I love the gif!

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Postby xkcd » Fri Aug 04, 2006 6:01 pm UTC

Also, BAHAHAHA, I missed that, ArbiterOne!

So much love for Jurassic Park icons.

Let's see it again:

Image

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Postby ArbiterOne » Sat Aug 05, 2006 3:23 am UTC

It's from the icons on Movies in Fifteen Minutes.
Image

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Postby RealGrouchy » Sun Aug 06, 2006 3:12 pm UTC

The other funny thing about Jurrasic Park was that the two doctors' names were Dr. Grant and Dr. Harding, and I had a friend in school at the time who was crazy about dinosaurs, whose name was Grant Harding.

True story.

- RG>
Jack Saladin wrote:etc., lock'd
Mighty Jalapeno wrote:At least he has the decency to REMOVE THE GAP BETWEEN HIS QUOTES....
Sungura wrote:I don't really miss him. At all. He was pretty grouchy.

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Postby Charodei » Thu Aug 10, 2006 5:32 am UTC

The situation can be plotted on a standard Cartesian plane, with the human at the origin and the wounded raptor on the y-axis. The raptors' velocities are a pair of vectors parallel to the x- and y-axes, changing direction to aim at the human. The human will get and stay on a curve temporally equidistant from the (temporally) closest two raptors. Assuming that all actors begin at their maximum speeds (6, 10, and 25 m/s) simplifies the situation, but it looks like it's still a bunch of differential equations.

If the raptors lead their target (running to where the human will be, not where he is), it gets even uglier. The situation now brings in game theory, and there may not be a single optimal strategy for all players. (A textbook example of this is a baseball player whose batting average against different kinds of pitches (fastball, curveball, etc) varies depending on which one he's expecting. The optimal strategy is randomly throwing and expecting each kind of pitch a certain, non-intuitive percentage of the time (e.g. throwing 64% fastballs, 36% curveballs; expecting 80% fastballs, 20% curveballs).)

Messy stuff, which I don't want to deal with at 1:30 am. Currently, my best answer is "The solution to this problem will become irrelevant in less than five seconds."

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Dino Movies For Kids

Postby Sandalphon » Thu Aug 10, 2006 8:00 pm UTC

What? The fourteen-or-so Land Before Time movies weren't enough for you, Randy? I really wish that were a hyperbolic statement and there weren't around that many sequels...

No good new ones? Seek out old ones! Like... Rex: Kyoryu Monogatari. It's Japanese and live action, bound to be classic. No good new dinosaur video games? How about "Cadillacs and Dinosaurs." That was entertaining. And there's the 2004 short film, "Dinosaurs: They Sure Were Big." Chad Newman plays a brilliant role as "Dead Guy."

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Postby Guest » Tue Aug 15, 2006 1:51 am UTC

After calculations, 1) seems to be approx. 6.217 s, or Image to be exact. This is assuming the human instantly reaches top speed of 6 m/s, as inferred in the comic. I haven't looked at 2) yet.

I probably killed this didnt I :roll:

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Postby seraph283 » Tue Aug 15, 2006 1:53 am UTC

Oops forgot to log in

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Postby ulnevets » Tue Aug 15, 2006 5:01 am UTC

except for the initial attack, one person dies each time dinosaurs attack.

this is the fundamental rule of jurassic park.

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Postby xkcd » Tue Aug 15, 2006 5:33 am UTC

except for the initial attack, one person dies each time dinosaurs attack.

this is the fundamental rule of jurassic park.

Final raptor attack starting from when Grant brings the kids in and says "sit here" and they're eating Jello and the raptors creep up in silhouette: no deaths.

There are others that aren't as definitely 'one attack', like the one jumping at Sattler in the maintenance tunnel (got Muldoon earlier) and the one chasing the jeep (could be counted as part of the earlier attack with the lawyer).

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Postby ulnevets » Tue Aug 15, 2006 3:43 pm UTC

xkcd wrote:
except for the initial attack, one person dies each time dinosaurs attack.

this is the fundamental rule of jurassic park.

Final raptor attack starting from when Grant brings the kids in and says "sit here" and they're eating Jello and the raptors creep up in silhouette: no deaths.

There are others that aren't as definitely 'one attack', like the one jumping at Sattler in the maintenance tunnel (got Muldoon earlier) and the one chasing the jeep (could be counted as part of the earlier attack with the lawyer).

it's more of a general guideline, but it applies for all three movies. the first attack strands the group and reduces it to about 8 people. after that, one of the less significant persons dies in each attack until 3-4 people escape the island.

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Postby twenty10 » Wed Aug 16, 2006 4:22 am UTC

fundamental rule... general guideline.

you = Imageer
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Postby Penguin » Wed Aug 16, 2006 6:15 pm UTC

... you = patriotic jeweled sandal-er?

I don't get it!
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Postby DaveFP » Wed Aug 16, 2006 6:18 pm UTC

That's not a sandal, it's a Image!
Image

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Postby Penguin » Wed Aug 16, 2006 6:20 pm UTC

A diagram?

... Oh, that makes so much more sense!
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Postby davean » Wed Aug 16, 2006 11:29 pm UTC

DaveFP wrote:That's not a sandal, it's a Image!


Of course, we all wear NAND latchs on our feet ...

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Postby RealGrouchy » Thu Aug 17, 2006 1:47 am UTC

Ohhh! I get it, it's a

highlight to read wrote:flip-flopper!


Cute. That ties into the whole soiling-one's-flag-with-one's-dirty-feet comment I would otherwise have made if I didn't get it.

- RG>
Jack Saladin wrote:etc., lock'd
Mighty Jalapeno wrote:At least he has the decency to REMOVE THE GAP BETWEEN HIS QUOTES....
Sungura wrote:I don't really miss him. At all. He was pretty grouchy.

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Java Simulation for Problem 2

Postby mat_the_w » Thu Sep 07, 2006 1:08 pm UTC

Hello everyone! A few of us nerds wrote a java simulation to try to find the most effective run path for problem number 2. You can view our write-up at my website, at http://www.tc.umn.edu/~beck0778/velociraptors/velociraptors.html

Enjoy,
Matthew

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Postby xkcd » Thu Sep 07, 2006 3:42 pm UTC

Matt, you should repost that as its own topic so it's easier to link to. Also because it's pretty cool!


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