Density Measurement Methods

Measuring density accurately is essential in material science, quality control, and many industries. Methods range from the ancient Archimedes principle to modern digital analyzers, each suited to different materials and precision requirements.

Water Displacement Method

Based on Archimedes' discovery—submerge an object and measure displaced water.

Procedure

1. Weigh the object (mass m)
2. Fill graduated cylinder with known water volume (V₁)
3. Submerge object, read new volume (V₂)
4. Volume of object = V₂ - V₁
5. Density = m / (V₂ - V₁)

Best For

• Irregular solid objects
• Educational demonstrations
• Quick estimates

Hydrometer

A floating device that measures liquid density directly.

How It Works

• Weighted bulb floats at depth proportional to liquid density
• Scale reads density directly
• Denser liquid = floats higher

Applications

• Battery acid strength
• Alcohol content (brewing)
• Antifreeze concentration
• Urine specific gravity (medical)

Digital Density メートル

Modern oscillating tube instruments provide high precision.

How They Work

• Sample fills U-shaped vibrating tube
• Vibration frequency depends on mass
• Electronics calculate density automatically

Advantages

• High precision (to 0.00001 g/cm³)
• Small sample needed
• Temperature controlled
• Quick measurement

まとめ

Density measurement methods range from simple water displacement to sophisticated digital meters. The choice depends on required precision, sample type, and available equipment. For liquids, hydrometers provide quick readings; for solids, water displacement or pycnometers work well; for high precision, digital density meters are preferred.

関連記事

• 理解する Density: Mass, Volume, and Why Things Float
• Density in Materials: 変換元 Aerogels to Osmium