Scores

chalker
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Re: Scores

Post by chalker »

kinghong1970 wrote:i think many teams came in with the impression that their bridge NEEDS to hold 15kg.

my daughters' bridge tests at home started at 5.06g with total load of 3089gr and latest before contest came in at 3.52g which held 2754g

was hoping to break 2k... definitely possible... but alas, event is over for them.
This triggered an interesting thought experiment in my head: I wonder if it's possible to be competitive by making the lightest bridge possible that ONLY supports the loading block. Here's a rough analysis:

-Last year at Nationals, the 6th place team in Div B got a score of 3288, while the 6th place team in Div C got a 2466.
-The loading block is 5 cm x 5 cm x ~2cm = ~50 cm^3
-Assuming it's made out of Pine, which is common for lumber, the density is ~500 kg / m^3
-Thus the loading block will weigh ~25 g

To place at Nationals, bridges would need to weigh:
Div B: 25 / 3288 = 7.6 mg
Div C: 25 / 2466 = 10.1 mg

So is that even possible? Well:
-the lightest readily available balsa wood has a density of ~70 kg / m^3
-likewise, the smallest cross section you can get is 1/32" x 1/32" (0.8mm x 0.8mm) = 0.64 mm^2
-Thus, this super light and thin balsa will weigh 44.8 ug / mm = 0.448 mg / cm

Using the above weights, and assuming no glue weight, you'd be able to use:
Div B: 7.6 / 0.448 = 16.9 cm
Div C: 10.1 / 0.448 = 22.5 cm

Which in neither case is sufficient length for even a single stick to span the required clear span areas (35cm and 45cm). Just to have 2 bare sticks spanning the gap would require 4 times the length/mass, resulting in 1/4 the score, which in itself wouldn't likely place at virtually any regional competition.

Hence, supporting only the loading block with the lightest possible bridge is NOT a competitive technique by any stretch of the imagination.

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Re: Scores

Post by Bazinga+ »

chalker wrote:
kinghong1970 wrote:i think many teams came in with the impression that their bridge NEEDS to hold 15kg.

my daughters' bridge tests at home started at 5.06g with total load of 3089gr and latest before contest came in at 3.52g which held 2754g

was hoping to break 2k... definitely possible... but alas, event is over for them.
This triggered an interesting thought experiment in my head: I wonder if it's possible to be competitive by making the lightest bridge possible that ONLY supports the loading block. Here's a rough analysis:

-Last year at Nationals, the 6th place team in Div B got a score of 3288, while the 6th place team in Div C got a 2466.
-The loading block is 5 cm x 5 cm x ~2cm = ~50 cm^3
-Assuming it's made out of Pine, which is common for lumber, the density is ~500 kg / m^3
-Thus the loading block will weigh ~25 g

To place at Nationals, bridges would need to weigh:
Div B: 25 / 3288 = 7.6 mg
Div C: 25 / 2466 = 10.1 mg

So is that even possible? Well:
-the lightest readily available balsa wood has a density of ~70 kg / m^3
-likewise, the smallest cross section you can get is 1/32" x 1/32" (0.8mm x 0.8mm) = 0.64 mm^2
-Thus, this super light and thin balsa will weigh 44.8 ug / mm = 0.448 mg / cm

Using the above weights, and assuming no glue weight, you'd be able to use:
Div B: 7.6 / 0.448 = 16.9 cm
Div C: 10.1 / 0.448 = 22.5 cm

Which in neither case is sufficient length for even a single stick to span the required clear span areas (35cm and 45cm). Just to have 2 bare sticks spanning the gap would require 4 times the length/mass, resulting in 1/4 the score, which in itself wouldn't likely place at virtually any regional competition.

Hence, supporting only the loading block with the lightest possible bridge is NOT a competitive technique by any stretch of the imagination.
I heard stories about how one year some invitational was running bridges and used a scale which couldn't measure masses less than 1 gram, so it would read 0 grams at 1 gram, and one team brought 2 very light sicks of balsa which held the block and the bucket and then quickly collapsed, and ended up getting first with an efficiency of INFINITY (mass held/0 grams). Not really too helpful but just a funny story about this strategy.
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Re: Scores

Post by noobforce »

At NJ States, 1st place has a 2400s efficiency and second place was 2250.
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Re: Scores

Post by xinu777 »

At NC Charlotte-Regional just completed today, Jay M. Robinson got first place with 3363 efficiency in Div. B.
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Re: Scores

Post by Unome »

xinu777 wrote:At NC Charlotte-Regional just completed today, Jay M. Robinson got first place with 3363 efficiency in Div. B.
Looks like we'll be seeing some more 4000+ scores at Nationals :)
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Re: Scores

Post by nxtscholar »

noobforce wrote:At NJ States, 1st place has a 2400s efficiency and second place was 2250.
To clarify, that's for division C.

And congrats once again :P
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Re: Scores

Post by S4BB »

We had our regional yesterday, JV teams took 1st and 4th with 3461 and 2400ish, Varsity took second with a little over 3000, all broke early. Division B
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Re: Scores

Post by dholdgreve »

Top 3 Bridges at the Piqua, Ohio Regional, Division B were all over 3300
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Re: Scores

Post by SPP SciO »

Totally stymied by these 3k+ bridges - hats off to those teams. To imagine less than 5g of balsa supporting a bucket that's heavy for a person to hold - wow.

At the NYC regional, 832 was good enough for a 6th place medal! Arched bridges seemed to win the day but I have no idea about the top placing scores.
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Re: Scores

Post by JZhang1 »

wtf why is everyone so good :!:

Weight: 3.33 g
Held: ~9
Efficiency: ~2600
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