예술
뷰티 및 웰니스
공예
문화 및 역사
엔터테인먼트
환경
음식 및 음료
역공학
과학
스포츠
기술
웨어러블
Testing a Gold Crown with Water — Archimedes' Buoyancy and the Eureka Method
King Hiero of Syracuse suspected his goldsmith had cut his crown with cheaper silver, but how do you check without melting it down? Around 250 BC Archimedes solved it in the bath: stepping in, he saw the water rise by his own volume and realised a submerged object displaces its own volume of water. Density — weight divided by volume — then betrays any cheating, because gold is far denser than silver. This blueprint reproduces both the famous displacement test and Archimedes' more precise underwater-balance method, and states the buoyancy principle that floats every ship.
중급
2
안내
1
1
Understand the problem
Understand the problem
You must find whether a crown is pure gold without damaging it. The key is density — weight divided by volume. Pure gold is very dense (about 19.3 g/cm³); gold mixed with lighter silver (about 10.5 g/cm³) is less dense, so the same weight of it takes up more space.
2
2
The Eureka insight
The Eureka insight
When a solid is lowered into water it pushes aside — displaces — exactly its own volume of water. So even an oddly shaped crown's volume can be measured by how much water it displaces. This is what Archimedes realised watching the bath overflow.
3
3
Set up an equal-arm balance
Set up an equal-arm balance
Hang a balance scale, or make an equal-arm balance from a rod and string with a small pan on each end, so it swings level and can compare two weights precisely.
필요한 도구:
Balance Scale4
4
Balance the crown against pure gold in air
Balance the crown against pure gold in air
On the balance, set the crown against an equal weight of known pure gold, in air, until the two sides hang exactly level. Now they weigh the same — the only question left is whether they take up the same volume.
이 단계의 재료:
Crude Lead Ingot (from galena smelting)1 개필요한 도구:
Balance Scale5
5
Submerge both in water
Submerge both in water
Lower both objects, still on the balance, into a vessel of water. Each is pushed up by a buoyant force equal to the weight of the water it displaces — the bulkier object is pushed up harder.
이 단계의 재료:
Water5 리터필요한 도구:
Clean Glass Jars with Lids
Cotton Kitchen String6
6
Read the verdict
Read the verdict
If the crown is pure gold it has the same volume as the gold and the balance stays level under water. If it is adulterated with lighter silver it is bulkier, displaces more water, is buoyed up more, and its side rises — proof the crown is not pure gold.
필요한 도구:
Balance Scale7
7
Or measure density directly
Or measure density directly
The simpler displacement version: weigh the crown, then submerge it in a brim-full vessel and measure the overflow — that volume is the crown's volume. Density = weight ÷ volume. Compare to pure gold's 19.3 g/cm³; an adulterated crown reads lower.
필요한 도구:
Clean Glass Jars with Lids8
8
State Archimedes' principle
State Archimedes' principle
Any body in a fluid is pushed up by a force equal to the weight of the fluid it displaces. That single law tells the crown from a fake, floats a loaded ship, and lifts a balloon — one of the oldest exact laws of physics, from around 250 BC.
관련 블루프린트
이 블루프린트들은 지식을 공유합니다 — 기술, 재료 또는 원리
CC0 퍼블릭 도메인
이 블루프린트는 CC0로 공개되었습니다. 어떤 목적으로든 자유롭게 복사, 수정, 배포 및 사용할 수 있습니다.
제품 구매를 통해 메이커를 지원하세요. 판매자가 설정한 메이커 커미션 을 받거나, 이 블루프린트의 새로운 반복을 만들어 연결로 포함시킬 수 있습니다.