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 Replies: 18 / Views: 3,145 |
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Pillar of the Community
  United States
7963 Posts |
Quote:
Ingenious way to weight a coin I'm an engineer. Gets me in trouble sometime  But I'm also cheap, so using a little physics means I don't need to spend money on a scale/balance. I have seen the composition of this coin listed as billon and mass at 4 g. Also, the auction house was a reliable one in Italy, and probably knows this type well, and would recognize a fake. Edited by tdziemia
08/13/2018 8:08 pm
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Valued Member
Romania
86 Posts |
No, no, no, don't get me wrong, I do not doubt your coin, I was thinking about mine. If I remember right, I already labeled it fake. With your permission, maybe I will post a pic in your post later today/ tomorrow.
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Pillar of the Community
United States
7963 Posts |
Sure! I'm not an expert on fakes, but I am sure others will offer an opinion.
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Valued Member
United States
217 Posts |
Very nice addition and interesting that Thomas only appears on pieces from those particular locales. Do you have your set imaged online? I am intrigued by your collection focus, as I collect a similar theme.
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Pillar of the Community
United States
7963 Posts |
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Valued Member
Romania
86 Posts |
I remembered correctly, only 2.61g, so probably fake.   Edited by bogdanjovi
08/15/2018 09:07 am
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Pillar of the Community
United States
7963 Posts |
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Valued Member
Romania
86 Posts |
Still, the weight is completely off.
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Pillar of the Community
Russian Federation
5178 Posts |
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It took me a few minutes to set up my balance Ha, funny, I use a similar system! (Well, formerly used a similar system until I got the nice pocket scale I use today.) |
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Pillar of the Community
United States
7963 Posts |
It's just not true that the stuff we learn in school isn't useful.  Sometimes I have bought a coin where the seller gives an accurate weight. Sometimes I have access to a good balance. And sometimes I use this method, which depends only on having one coin (or other object) with a known mass. In this case, a modern U.S. cent should be very close to 2.50 g. and the ruler can be read to 0.5 mm, so the mass of the unknown coin should be good to 2 significant figures. |
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Pillar of the Community
Russian Federation
5178 Posts |
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And sometimes I use this method, which depends only on having one coin (or other object) with a known mass. In this case, a modern U.S. cent should be very close to 2.50 g. and the ruler can be read to 0.5 mm, so the mass of the unknown coin should be good to 2 significant figures. This is not actually quite true - at least in my version - because it's hard to position the ruler exactly right (and it tends to slip a bit anyway), and it's hard to read where exactly the two coins are (especially if the coin being measured isn't quite round, which is common for ancients and some medievals). It helps somewhat to do several tries with different counterweight coins (of different known weights) - those are effectively independent measurements and can be averaged together. (Also, if I'm reading your balance right, it's showing a measurement of circa 3.6-3.7 grams. Where does the 3.8 come from?) |
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Pillar of the Community
United States
7963 Posts |
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if I'm reading your balance right, it's showing a measurement of circa 3.6-3.7 grams. Where does the 3.8 come from? I used these positions: fulcrum = 7.5 cm 1 cent = 14.0 cm 20 soldi = 3.2 cm Mass of 1 cent = 2.50 g. So, 2.50*(14.0-7.5)/(7.5-3.2) = 3.78 g. rounded to 3.8. If one of the positions is read differently by 0.1 cm, you could get the result you obtained. I agree completely with the sources of error in the measurement that you've pointed out. Still, in this case, we both reach a result which is not more than 10% different from the "published" value. I'll check the mass in one week when I will have access to a laboratory balance (school starts on Aug. 27 |
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Pillar of the Community
Belgium
1194 Posts |
very interesting system to fix the weight of a coin . Mine is very easy : I bought a kitchenbalance in the form of a spoon with digits in the supermarket for 2.5€ , I checked it later with a a real digital balance and the difference in 10 tests was less then 0.01 gram .albert
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Pillar of the Community
United States
7963 Posts |
I must look for something like that. Definitely within my budget |
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Pillar of the Community
Belgium
1194 Posts |
and you never loose your coin ....... albert  .... |
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Replies: 18 / Views: 3,145 |
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Posted 08/13/2018 7:38 pm
