Author Topic: Gravity in Schome Park  (Read 23496 times)

Offline Explo Schomer

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Gravity in Schome Park
« on: March 17, 2007, 08:19:51 PM »
Just thought I could give some of my findings and see what other people have found out.

First, objects appear to have set mass, regardless of their size or material. Putting a large cube and a small cube on a balance at equal distance they balanced, and putting a wooden cube and a stone cube on the balance at equal distance they balanced. This effect can also be seen through catapults-a small 'ammo' cube will go to the same height as the larger 'launching' cube was dropped from.

Second, air resistance seems to be non-existent. I'm sure you will have noticed that if you knock against the ring chains they carry on swinging for at least a long time, if not forever. I have also dropped a flat wooden block at the same time and height as a wooden cube and they hit the ground at the same time.

Third, just as each object has a set mass, two objects will have twice that mass, with my first point applying. Putting two wooden cubes half the distance from the pivot from one wooden cube makes them balance, while putting them at the same distance away from the pivot makes the balance tip towards the two cubes.

Fourthly, the law of moments appears to work just as it does in real life. A wooden cube further from the pivot tips the balances against an identical cube closer to the pivot.

Experiments I am planning for future are testing whether gravity creates acceleration, or simply makes an object fall at a set speed and numerical data must be found for whichever of these holds true (eg what the set speed is). Personally I think it will be a set speed, but we need to test this.

Any findings by anyone else?
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Offline PeterT

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Re: Gravity in Schome Park
« Reply #1 on: March 17, 2007, 09:22:34 PM »
Just thought I could give some of my findings and see what other people have found out.
...

 8) Nice work Explo - once you're ready it would be great to document this on a page in the wiki ...

PeterT

Offline Decimus Schomer

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Re: Gravity in Schome Park
« Reply #2 on: March 17, 2007, 10:53:27 PM »
Experiments I am planning for future are testing whether gravity creates acceleration, or simply makes an object fall at a set speed and numerical data must be found for whichever of these holds true (eg what the set speed is). Personally I think it will be a set speed, but we need to test this.
At least for avatars, it creates acceleration. I found this because I have the Flight Feather, which tells you how fast you are moving. It increases at around 10m/s/s.
And I made a test which applied a constant upwards force and it moved around (???) at 9.8m/s/s, but only moved up at greater than that.

I conclude that SL gravity is 9.8m/s/s

Offline Faji

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Re: Gravity in Schome Park
« Reply #3 on: March 17, 2007, 11:24:31 PM »
one of the initial musings of mine when building the cannon was that we could shoot stuff around and see how well we could model projectile motion, all we need is a very long ruler.............
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Offline Explo Schomer

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Re: Gravity in Schome Park
« Reply #4 on: March 18, 2007, 09:31:53 PM »
Just thought I could give some of my findings and see what other people have found out.

First, objects appear to have set mass, regardless of their size or material. Putting a large cube and a small cube on a balance at equal distance they balanced, and putting a wooden cube and a stone cube on the balance at equal distance they balanced. This effect can also be seen through catapults-a small 'ammo' cube will go to the same height as the larger 'launching' cube was dropped from.

I've found the opposite: that mass varies depending on the objects volume. Larger objects seem to have more mass than smaller objects (as you would expect), but two objects with a volume of 0.125m cubed seem to have a larger mass than one object with a volume of 0.25m cubed. The difference is small, but it's noticeable and all the tests I've done so far confirm it. Material, however, doesn't seem to change the mass of the object (though I'm not quite sure what it does change)

Oh, and modelling projectile motion could be done using a catapult (I've built one and Mirage Schomer is building one, so we'll have two designs to work with)  :)
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Offline Decimus Schomer

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Re: Gravity in Schome Park
« Reply #5 on: March 18, 2007, 09:45:54 PM »
Material, however, doesn't seem to change the mass of the object (though I'm not quite sure what it does change)
I think all the "material" is is just what textures have been applied to it. Think of a box painted to look like wood and another that's painted like a metal - they'll have the same mass.

Offline Troubleat Mills

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Re: Gravity in Schome Park
« Reply #6 on: March 19, 2007, 04:10:10 PM »
I think all the "material" is is just what textures have been applied to it. Think of a box painted to look like wood and another that's painted like a metal - they'll have the same mass.
This was an observation I made as well Decimus. When I built my linked rings I made each one of them of a different material/texture, but when pulled they all behave in the same way.

Slightly off-topic and you've probably discovered it by now anyway, but I got a big fat Latin dictionary out and looked up the word dragon. It's draco, (draconis), meaning serpent or dragon.
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Offline Decimus Schomer

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Re: Gravity in Schome Park
« Reply #7 on: March 19, 2007, 05:09:22 PM »
Slightly off-topic and you've probably discovered it by now anyway, but I got a big fat Latin dictionary out and looked up the word dragon. It's draco, (draconis), meaning serpent or dragon.
I didn't find that. Thanks. I'll remember that next time I want to tell someone's dragon to go away :p

Offline Marko Schomer

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Re: Gravity in Schome Park
« Reply #8 on: March 19, 2007, 08:02:41 PM »
I think all the "material" is is just what textures have been applied to it. Think of a box painted to look like wood and another that's painted like a metal - they'll have the same mass.

The material is separate from the texture, and can be edited on the Object section of the build menu. It doesn't affect appearance, and doesn't seem to affect anything else (though there may be some difference in how landings are modelled. I don't know)

Offline Explo Schomer

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Re: Gravity in Schome Park
« Reply #9 on: March 19, 2007, 08:29:43 PM »
My earlier findings were wrong, in that different volumes do result in different masses. This appears to be roughly linear but there are variations, and I haven't managed to track down the exact variance yet.

I have also found out what the repulsive force between objects is. Every object, unless it is phantom, protudes a form of forcefield of size 0.05m around it. This means that any two objects where one is physical (non-physical objects will not move to leave this force field, essentially intersecting each other) will always be seperated by a space of 0.1m, although this gap varies +/- 0.01. I didn't think it was worth starting a new topic on this, as it is a rather small field to investigate.
« Last Edit: March 19, 2007, 08:35:02 PM by Explo Schomer »
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Offline Decimus Schomer

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Re: Gravity in Schome Park
« Reply #10 on: March 19, 2007, 09:09:44 PM »
I have also found out what the repulsive force between objects is. Every object, unless it is phantom, protudes a form of forcefield of size 0.05m around it.
That's interesting.

By the way, I wonder which forces are modelled in SL. Because it's intended to be a life simulator, there probably won't be EM (it'll be very loosely simulated by basically stopping objects moving together), Strong or Weak forces, as these only really affect things on tiny scales.

On this subject, I thought of something interesting - we might be able to set up a program that would simulate a universe. The implications of this is that we might be in one of these. This leads to an interesting question: If our universe is being run on a server, why do you think it is?  ;)

Offline Rufus Schomer

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Re: Gravity in Schome Park
« Reply #11 on: March 19, 2007, 09:50:33 PM »
By the way, I wonder which forces are modelled in SL.
Bouyancy isn't and nor is fluid friction; the only difference being underwater makes is things are bluer and darker.

Offline mgaved

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Re: Gravity in Schome Park
« Reply #12 on: March 19, 2007, 10:52:36 PM »
Quote
This leads to an interesting question: If our universe is being run on a server, why do you think it is?


I don't know but I just hope it's not running Windows if it is ...  >:D
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Offline Wolf (aka Mirage)

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Re: Gravity in Schome Park
« Reply #13 on: March 20, 2007, 07:11:17 AM »
hmm... i can't imppose gravity on my trebuchet. can anyone help?
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Offline Marko Schomer

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Re: Gravity in Schome Park
« Reply #14 on: March 20, 2007, 10:01:21 AM »
hmm... i can't imppose gravity on my trebuchet. can anyone help?

Make the components of the trebuchet that you want to be affected by other objects and by gravity physical, by going on to the "Object" tab on the "More..." menu, and ticking the "physical" box. This applies to the arm of the trebuchet, the block you are trying to throw, and the counterweight. If you want to see an example you can look at my catapult at point 75 on the y axis, 100 on the x axis, and 100 on the z axis (near the small moon). It's built on a different mechanism to yours, but the basics are the same. I'll try to make it available to everyone this evening, so anyone can take a copy.