Relative mass of various materials

[DaveH]

I was interested in the relative mass of the various materials so I did some research by constructing a scale balance and then hanging various materials from it. I thought I'd share the results which some of you may find useful when fine tuning various solutions.

For starters, I had to decide some arbitrary units of measure and I decided to use percentages of the armadillo itself. So, if the armadillo is represented by 100% then 50% would be half that mass and 200% would be double. (If your brain gets addled by percentages then just think of the numbers as representing ounces, pounds, kilos or whatever you prefer.)

Short vs. Long
Some materials can have a range of sizes between each link (for a fixed price). I have given the relative mass of the shortest and longest length of a single section.

Compression and Tension
Compression and Tension on a material will change its mass for the same length. That's because there is actually more or less material that has been squashed or stretched to the desired length. Although most materials can be compressed or stretched by various amounts, I've only given the values for full compression/tension of elastic and rubber.

Rockets
Rockets deserve a special mention. They have their own mass, depending on length, but also have a thrust value whcih can increase or decrease it's effective weight. In simple terms, the effective weight is the mass plus the thrust if pointing down and the mass minus the thrust if pointing up (if the effective weight goes negative, the rocket defies gravity and moves upward).

Variable length materials without links

Short elastic: 6%; compressed 30%; tensioned 4%
Short rope: 8%
Short cloth: 12%

Fixed price materials (per link)

Short metal bar: 12%
Short metal sheet: 20%
Short rubber: 16%; compressed 28%; tensioned 12%
Long metal bar: 60%
Long metal sheet: 100%
Long rubber: 80%; compressed 140%; tensioned 60%

Other

Short rocket: 46%; thrust 130%; max lift 84%; max weight 176%
Long rocket: 240%; thrust 760%; max lift 520%; max weight 1000%
Armadillo: 100%

Dave.

[BFC]

Cool stuff Dave

I did something similar and less exact on my own a while back to determine if metal sheets vs bars was heavier per unit of cost. Bars won and your results back that up.

I'm sure we'll put this info to good use in the future!

-BFC

[PeterT]

Great work! I wanted to do something like this as well but was always too engrossed in solving levels and tweaking for contests.

This will prove useful in the future

[Ogre]

Cool stuff Dave

I did something similar and less exact on my own a while back to determine if metal sheets vs bars was heavier per unit of cost. Bars won and your results back that up.

Yep, I got a lot of testing on the weight of bars vs. sheets for contest #3. Two bars were clearly heavier than one sheet, for the same price.

But that was as far as I got, nice work on this

[kingofthespill]

Interesting - I did the exact same thing. I thought the metal sheet was just shy of 100 percent.

[kingofthespill]

In case anyone is interested another thing I did was test drag. One interesting thing is that it's independent of orientation! Probably much easier to program that way.

The drag was greatest on cloth, followed very quickly by rope and elastic. All 3 had less drag on the node ends. All the heavier stuff is much less affected but were a bit different one another: metal sheet, metal rods, rubber, and armoredillo the least.