សិល្បៈ
សម្រស់ និង សុខុមាលភាព
សិប្បកម្ម
វប្បធម៌ និង ប្រវត្តិសាស្ត្រ
ការកម្សាន្ត
បរិស្ថាន
ម្ហូប និង ភេសជ្ជៈ
អនាគតបៃតង
វិស្វកម្មបញ្ច្រាស
SCHOOL PROJECTS
វិទ្យាសាស្ត្រ
កីឡា
បច្ចេកវិទ្យា
ប្រដាប់ដែលស្លៀក
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.
មធ្យម
2
ការណែនាំ
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.
Tools needed:
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.
Materials for this step:
Crude Lead Ingot (from galena smelting)1 pieceTools needed:
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.
Materials for this step:
Water5 literTools needed:
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.
Tools needed:
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.
Tools needed:
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.
You can swap these in
Can't get one of the materials? Swap it for an equivalent — these work just as well.
- Instead of Water, try:
Distilled Water (1 Liter)
Distilled Water - Instead of Balance Scale, try:
Iron Scale
Livestock Scale
Weighing Scale
Precision Scale
Digital Precision Scale
Platform Weighing Scale
Digital Scale (0.01g)
Digital Kitchen Scale - Instead of Clean Glass Jars with Lids, try:
Glass Bottles with Lids - Instead of Crude Lead Ingot (from galena smelting), try:
Bronze Ingot
Recommended for this build
Products makers often use with builds like this one.
Desktop ComputerUsed together and in similar builds
PaperUsed together and in similar builds
Cloth (Straining)Frequently used with this build's materials
Graphite Pencil SetUsed together and in similar builds
Glass MullerFrequently used with this build's materials
Large Cooking PotFrequently used with this build's materials
Stone Mortar and Pestle (large)Frequently used with this build's materials
Chemical Splash GogglesFrequently used with this build's materialsប្លង់ពាក់ព័ន្ធ
ប្លង់ទាំងនេះចែករំលែកចំណេះដឹង — បច្ចេកទេស សម្ភារៈ ឬគោលការណ៍
Related blueprints
Other builds that share materials, tools, or techniques with this one.
Forging an Iron Fish Hook — Drawing, Bending, and Barbing Wire StockMetalworking
Dyeing Yellow-Brown with Sumac Leaves — The Tannin-Rich Dye of the Ancient Mediterraneantextiles
Carving a Wooden Spoon with Stone Tools and Ember Hollowing — The Universal Kitchen Toolwoodworking
Smelting Copper from Malachite — From Green Ore to Red Metalchemistry
The Law of the Lever — Archimedes' Balance of Weight and Distance
Casting a Bronze Socketed Spearhead — Bivalve Mould MethodMetalworking
CC0 សាធារណៈ
ប្លង់នេះត្រូវបានចេញផ្សាយក្រោម CC0។ អ្នកមានសិទ្ធិចម្លង កែប្រែ ចែកចាយ និងប្រើប្រាស់ដោយមិនចាំបាច់សុំអនុញ្ញាត។
គាំទ្រអ្នកបង្កើតដោយទិញផលិតផលតាមរយៈប្លង់របស់ពួកគេ ដែលពួកគេទទួលបាន កម្រៃជើងសារអ្នកបង្កើត កំណត់ដោយអ្នកលក់ ឬបង្កើតកំណែថ្មីនៃប្លង់នេះ ហើយបញ្ចូលជាការតភ្ជាប់ក្នុងប្លង់របស់អ្នកដើម្បីចែករំលែកចំណូល។