Constitution of little animals

[Gollum]

Hungry shrews. Be afraid. Be very afraid.

http://www.youtube.com/watch?v=rQSCkvNQfhA

This movie is amazing! Perfectly kitsch... I hope I'll find the time to watch it.

[rogerd]

Hungrier. And they want all your marbles, baby.

Aaaaaarrgh!!!!!

I rolled for San loss and got a 100---is that bad???

[Agentorange]

Not to be confused with these shrews:

Which are completely harmless

[Gollum]

So, I watched The Secret Life of the Cat, episode #12

It sounds to be a serious study made by serious scientists like professor Alan Wilson, specialist of feline tracking (Structure and Motion lab, Royal Veterinary College).

They used GPS trackers able to let know where the cats go, how far they go, what is their speed and what are their accelerations.

They did the experience in an English village, with 50 different cats, day and night across a whole week.

They also used cameras, both covered fixed one in the village and its neighborhood, and little ones, mounted on the cats, to try to see what they exactly did.

The conclusions are...

Some cats turn around home... Some other go to the neighbor wood... Some go to a neighbor house. The average cat's home range (maximum range from home) is about hundred meters for males and half that for females. The cat who has the widest walking territory covers an area of 300 meters times 200 meters and walks about 2 miles a day.

So, it sounds that I was completely wrong. Unless other episodes of this TV documentaries show the contrary (I only watched episode #12 and there are 17 different episodes), or unless I didn't understand numbers at all (English is not my native tongue and there was no subtitle).

Edited February 3, 2014 by Gollum

[Atgxtg]

Well Gollum, you're keeping me honest!

I stopped by the library this morning and picked up a couple of books on animals, including The Book of Animal Ignorance -Everything You Think You Know is Wrong, and I think it might help out with our animal stats. While the general trends against small animals seem to hold true, there are some notable exceptions, such as the Brown Rat (can store water better than a camel!).

BTW, as far as housecats go, they apparently spend about 85% of their time doing nothing; 5% of their time hunting, eating, playing, and all that; and 10% of their time going from place to place. It seems they are good at having multiple "homes" where they can get multiple feedings.

[Gollum]

Well Gollum, you're keeping me honest!

I've always considered than searching truth is much more important than being right. And fortunately, because life tend to show that being right is very relative! As latins said, "errare humanum est, sed peseverare diabolicum". Avoiding perseverare is eventually the most important.

I stopped by the library this morning and picked up a couple of books on animals, including The Book of Animal Ignorance -Everything You Think You Know is Wrong, and I think it might help out with our animal stats. While the general trends against small animals seem to hold true, there are some notable exceptions, such as the Brown Rat (can store water better than a camel!).

Yes. They are a lot of exceptions in the world of animals... But, as you showed it well, it doesn't prevent to have generic rules. To the contrary, these generic rules help the GM to assess most animal stats. And to twist them if he really thinks that a specific creatures has to be considered as an exception.

BTW, as far as housecats go, they apparently spend about 85% of their time doing nothing; 5% of their time hunting, eating, playing, and all that; and 10% of their time going from place to place. It seems they are good at having multiple "homes" where they can get multiple feedings.

That was in the documentary too: a lot of cats know when other cats are roaming and take advantage of it to get stealthily in their home in order to steal their food.

Edited February 3, 2014 by Gollum

[Atgxtg]

I've always considered than searching truth is much more important than being right. And fortunately, because life tend to show that being right is very relative! As latins said, "errare humanum est, sed peseverare diabolicum". Avoiding perseverare is eventually the most important.

Eeek! I know a lot of diabolists!

Yes. They are a lot of exceptions in the world of animals... But, as you showed it well, it doesn't prevent to have generic rules. To the contrary, these generic rules help the GM to assess most animal stats. And to twist them if he really thinks that a specific creatures has to be considered as an exception.

And sometimes a few little generic notes can help. For example, I think any warm-blooded animal that has fur, feathers, and/or a thick layer of fat should probably add 2 or 3 times their AP to their CON for resisting cold. Not that it will come up much.

Although I suppose if a character was using cold magic against a Polar Bear, we might want to give the bear 3x it's AP.

That was in the documentary too: a lot of cats know when other cats are roaming and take advantage of it to get stealthily in their home in order to steal their food.

Cat-burglars!

[Al.]

What is different is the time taken to reach this velocity, which is offset by drag and buoyancy. But once it is reached, terminal velocity is the same no matter what your size,

Ummm no

Otherwise we would not use parachutes.

Human without parachute approx 50m/s

Human with parachute approx 8m/s

A skydiver hits their terminal velocity and then not wanting to impact the ground at 50m/s deploys chute which increases drag. Drag now larger than weight. Resultant force acts in opposite direction to motion so skydiver decelerates. Carries on decelerating until reaches new terminal velocity (when drag and weight balance).

Edit: should have read to end of thread and seen that this had already been stated and acknowledged. Move along. Nothing to see here.

Edited February 3, 2014 by Al.

[Atgxtg]

Hmm, if we ignore most of the other factors, and just stick to mass, terminal velocity is proportional to the square root of mass, and the impact is velocity times mass, so impact damage would be tied to 1.5 times SIZ.

[seneschal]

"Terminal velocity." Sounds like a summer beach thriller. Can we get Peter Benchley or Clive Cussler to write that?

[Michael Hopcroft]

On the Hero boards, I once posited a spell called "Rain of Cows". This spell caused a downpour of (temporarily) live cattle over the area of its effect -- you're basically dropping cows on your enemies.

I describe the effect of having one land on you as "the same as had a cow fallen on top of you from several thousand feet in the air under normal circumstances". Now I'm wondering what that would be.

The only defense I can think of is getting out of the way when you hear that panicked mooing from the sky....

[Atgxtg]

"Terminal velocity." Sounds like a summer beach thriller. Can we get Peter Benchley or Clive Cussler to write that?

To me it sounds like how fast the plane travels while getting out of the airport!

[Gollum]

Hmm, if we ignore most of the other factors, and just stick to mass, terminal velocity is proportional to the square root of mass, and the impact is velocity times mass, so impact damage would be tied to 1.5 times SIZ.

Could you explain your calculation, please? What I have learned in my physics class is this:

1 = step before the fall.

2 = step after the fall.

KE = Kinetic energy

PE = Potential energy

m = mass

s = speed

z = difference of heights.

Law of conservation of energy: energy at step1 is the same than energy at step2.

KE1 + PE1 = KE2 + PE2

1/2ms1² + mgz1 = 1/2ms2² + mgz2

m (1/2s1² + gz1) = m(1/2s2² + gz2)

1/2s1² + gz1 = 1/2s2² + gz2

1/2s2² + gz2 = 1/2s1² + gz1

1/2s2² = 1/2s1² + gz1 – gz2

s2² = 2 (1/2s1² + gz1 – gz2)

s2 = square root of: 2 (1/2s1² + gz1 – gz2)

The mass is canceled in final the equation. So speed is really independent of it. This is, in my humble opinion, what Rogerd wanted to say and what has effectively be proven numerous time – either by the calculation of energy just above and by experimentation: two balls perfectly round and having exactly the same size fall at exactly the same speed and reach the ground at exactly the same time (if they are released from the same height at the same time); and that, independently of their mass. Their acceleration only depends on local g.

But the terminal velocity still depends of atmospheric friction. Which is relative to the shape and the size of the object. And this is where things become much more complicated. So, how did you come to 1.5 times SIZ?

Edited February 5, 2014 by Gollum

[Michael Hopcroft]

Hmm, if we ignore most of the other factors, and just stick to mass, terminal velocity is proportional to the square root of mass, and the impact is velocity times mass, so impact damage would be tied to 1.5 times SIZ.

So if a cat falls on you it hurts a bit.

I imagine if a cow falls on you, it hurts a lot.

[Atgxtg]

So if a cat falls on you it hurts a bit.

I imagine if a cow falls on you, it hurts a lot.

I said tied to, not equal to.

What I was doing was setting up a progression between SIZ and falling damage. Partially thinking "in text".

[Atgxtg]

Could you explain your calculation, please?

Glad to, although I did over simplify something and made two errors. I's down at the end. , It gets a bit technical though, so consider yourself warned!

What I have learned in my physics class is this:

1 = step before the fall.

2 = step after the fall.

KE = Kinetic energy

PE = Potential energy

m = mass

s = speed

z = difference of heights.

Law of conservation of energy: energy at step1 is the same than energy at step2.

KE1 + PE1 = KE2 + PE2

1/2ms1² + mgz1 = 1/2ms2² + mgz2

m (1/2s1² + gz1) = m(1/2s2² + gz2)

1/2s1² + gz1 = 1/2s2² + gz2

1/2s2² + gz2 = 1/2s1² + gz1

1/2s2² = 1/2s1² + gz1 – gz2

s2² = 2 (1/2s1² + gz1 – gz2)

s2 = square root of: 2 (1/2s1² + gz1 – gz2)

[Lord Sephleon]

Now I got a better equation that proves that girls are evil that would have been much more fun to read, but c'est la vie.

Oh, you also know the Rule of PIE?

[Gollum]

Now since I am dealing with impact damage, I am going to concentrate on the Force of the impact. For that we have the formula:

[…]

F=ma

[…]

F=(SIZ)a

[…]

Vt= sqrt{(2mg/(pACd)

[…]

V= sqrt(m)

[…]

V=sqrt(SIZ)

[…]

F=ma or F=SIZ*sqrt(SIZ)

[…]

Also, you can do multiplication and division on a logarithmic table with addition and subtraction! So in BRP stat terms we get F=SIZ+SIZ/2, or 1.5 SIZ. Ta-dahh!

Very well.

This is a rough approximation because you threw out the factor 2g/(pACd) which has a lot of incidence on falling terminal velocity. There would for instance be a lot of difference between me falling while wriggling and screaming crazily and Felix Baumgartner, who broke the sound barrier…

But no matter. This is still a very good approximation. And it was very clearly demonstrated. I had no problem to follow your equations.

Now, if we could have the time – and then, the height – required to reach that top speed, it could give a good formula to calculate the damage inflicted to someone who falls and by someone who falls on you.

GURPS fourth edition got close from that with its new rule about falling, falling objects and collisions which all use the same rule: a table gives the velocity you (or the falling object) reach depending on the height of the fall and, then, a simple calculation gives the damage inflicted depending on your starting hit points (or the starting hit points of the object falling on you): (velocity x starting hit points)/100 six-sided dice.

Unfortunately, it doesn't solve the problem of friction and drag... And the ant falling from 10 yards inflicts to itself about the same proportional damage than the elephant. Yet we know that it is wrong. The elephant would probably brake most of its bones while the ant would just be a bit surprised and, then, go on working and running without the least injury.

Now I got a better equation that proves that girls are evil that would have been much more fun to read, but c'est la vie.

Oh my! I've got an equation which proves that girls are angels.

Edited February 7, 2014 by Gollum

[soltakss]

In a roleplayuing game, you don't really need to consider different terminal velocities and drag coefficients, as most falls are short enough for them not to take effect. I'd simply have a maximum damage to the distance fallen representing the maximum velocity achievable.

But, I do like formulae and it is always interesting to see how they can be applied to games, so please don't stop.

[seneschal]

So ... is it the bad girl calculations or the good girl calculations you don't want to stop?

[Atgxtg]

In a roleplayuing game, you don't really need to consider different terminal velocities and drag coefficients, as most falls are short enough for them not to take effect. I'd simply have a maximum damage to the distance fallen representing the maximum velocity achievable.

Yup, especially in BRP, where one or two D6 is serious damage. We got sidetracked down this path when Gollum rightly pointed out that smaller animals would take less damage from a fall of a given distance than a larger animal due to their smaller mass. He even pointed out than small insects such as ants can take next to no damage from a fall because their low mass and high drag prevents them from hitting hard enough to really hurt them.

But the idea behind the terminal velocity stuff was just that the +1D6 extra falling damage per 20 SIZ in BRP actually makes sense, and a reducing damage might be worth implementing for small creatures.

But, I do like formulae and it is always interesting to see how they can be applied to games, so please don't stop.

LOL! Sorry for all the math. I actually did all the "calculations" in my head. That's one of the reasons why I came up with 1.5*SIZ instead of 1.75*SIZ. I really just wanted to see how much of an impact (sorry, couldn't resist the pun) SIZ has on falling damage, and dropped everything else from the equations to get an answer.

I usually simplify this stuff quite a bit before turning in into game mechanics. For instance the top speed formula for vehicles (the drag force equation) is pretty close to the formula for terminal velocity. The major difference is that you substitute the thrust of the engine for the force provided gravity and mass. But in BRP terms I simplified speed calculations down to about STR/2, or POW/3, each with a modifier. Which is much more acceptable.

[soltakss]

Yup, especially in BRP, where one or two D6 is serious damage. We got sidetracked down this path when Gollum rightly pointed out that smaller animals would take less damage from a fall of a given distance than a larger animal due to their smaller mass. He even pointed out than small insects such as ants can take next to no damage from a fall because their low mass and high drag prevents them from hitting hard enough to really hurt them.

But the idea behind the terminal velocity stuff was just that the +1D6 extra falling damage per 20 SIZ in BRP actually makes sense, and a reducing damage might be worth implementing for small creatures.

Yes, extra mass means more momentum, which means that the impulse on impact (Change in momentum) is higher. How much higher and what that means in terms of BRP game mechanics is always tricky to work out.

LOL! Sorry for all the math. I actually did all the "calculations" in my head. That's one of the reasons why I came up with 1.5*SIZ instead of 1.75*SIZ. I really just wanted to see how much of an impact (sorry, couldn't resist the pun) SIZ has on falling damage, and dropped everything else from the equations to get an answer.

My degree is in Pure Maths, so I don't mind formulae at all.

I tried doing something similar in the past, working out the Terminal Velocity and how many D6s that related to, but couldn't get a consistent answer. It was frustrating, to say the least. It is easier to make up the answer with nothing to back it up.

Spreadsheets are the key! No point working things out in your head, well my head anyway! You can try out the calculation using varying mass, distance and velocity that way. So much easier.

I usually simplify this stuff quite a bit before turning in into game mechanics. For instance the top speed formula for vehicles (the drag force equation) is pretty close to the formula for terminal velocity. The major difference is that you substitute the thrust of the engine for the force provided gravity and mass. But in BRP terms I simplified speed calculations down to about STR/2, or POW/3, each with a modifier. Which is much more acceptable.

Yes, I agree. Stick it into a table or simple formula and it is usable by everyone.

[Atgxtg]

Yes, extra mass means more momentum, which means that the impulse on impact (Change in momentum) is higher. How much higher and what that means in terms of BRP game mechanics is always tricky to work out.

Not so much. At least not now. Since I started that vehicle design project a few years back I did a bit of homework and eventually looked up to see how it really works instead of just trying to come up with something. To get tanks and battleships to work right I had to expand into weapons. Later into animals and so on. So I think I got a decent idea as how it works.

The key thing is understanding that BRP uses a logarithmic table for SIZ in the 8-88 range, and what some of the tricks you can do with logs.

My degree is in Pure Maths, so I don't mind formulae at all.

Yea! I tend to like doing things that way since it allows me to work up bunches of stats and have them being relatively consistient just by plugging in know data into a spreadsheet.

I tried doing something similar in the past, working out the Terminal Velocity and how many D6s that related to, but couldn't get a consistent answer. It was frustrating, to say the least. It is easier to make up the answer with nothing to back it up.

Yeah. One problem with BRP is that most of the rules were added piecemeal as the need came up, and usually not in a consistent manner. Falling damage, car crashes and such should all be on the same scale, but they aren't. Based on the STR+SIZ db, it seems that damage should increase by 1D6 for every quadrupling of the force, but falling damage uses 3m increments, and car crashes 10mph increments.

I think I did up a table that tried to reconcile it all into one formula. It would mean tweaking a few vales in the book, but would give us a consistent progression to use.

Spreadsheets are the key! No point working things out in your head, well my head anyway! You can try out the calculation using varying mass, distance and velocity that way. So much easier.

BINGO! I got hundreds of (mostly completed) vehicle stats done up in spreadsheets, and Erasmus has over a thousand critter stats done up in spreadsheets and databases using formulas.

Yes, I agree. Stick it into a table or simple formula and it is usable by everyone.