Using Euro coins as weights (2004)

Original Article ↗ Hacker News Discussion ↗

Coins as Convenient Physical Standards

  • Many comments note coins are mass‑produced with tight tolerances, making them handy approximate weights and length gauges.
  • Examples: euro cent stacks for grams; copper euro cents are all ~1.67 mm thick; US nickel ≈ 5 g; British 20p = 5 g; 1 JPY coin and US bills ≈ 1 g; 1 SEK = 7 g; Australian $1 = 9 g.
  • Several currencies have systematic designs:
    • Soviet kopecks (1, 2, 3, 5) weighed their face value in grams and had simple diameters.
    • British coins have rough proportionalities by value within groups (e.g., 1p/2p, 5p/10p).
    • US dime/quarter/half/dollar have neat weight relationships (e.g., each $20/lb).

Practical Uses and Hacks

  • Coins used to:
    • Calibrate cheap pocket or coffee scales (nickels; euro cents).
    • Provide reference areas in computer vision.
    • Build improvised balances from Lego.
    • Weigh drugs in school.
  • One person uses ~15 kg of euro cents as load in a weighted vest, acquired at face value from the central bank. Others mention pre‑rolled bank coin wrappers for neat “weight modules.”
  • Beach sand is suggested as free ballast, but others note containment hassles and legal/environmental limits on removing sand.

Accuracy, Wear, and Limitations

  • Debate over coin wear: some report almost no meaningful wear; others have coins with edges worn smooth and say that’s unacceptable as calibration standards.
  • Consensus: fine for low‑precision needs; not suitable for analytical‑grade measurement.
  • Water as a volume‑based mass standard is discussed; variability with temperature, salinity, etc., makes it unsuitable for very high precision.

Exercise with Weights

  • Thread diverges into weighted vests and limb weights.
  • Opinions split: some warn about joint strain and injury risk; others report safe use when weight is modest and progression is gradual.
  • Limb weights are considered riskier than vests due to leverage and momentum on joints.

Money, Weight, and Monetary Systems

  • Several remarks link currency names (pound, peso, shekel, penny, dime, quarter) to origins in weight or subdivisions.
  • Historical context: coins once embodied metal value; debasement and the shift to fiat are discussed, along with inflation and inequality debates.
  • A long subthread explores fiat vs commodity money, central‑bank policy, multiple currency types for different transaction classes, and seigniorage as a proxy for trust.