Lecture Notes: Density of Water

Introduction to Density

• Density is a physical property of matter.
• Formula: Density = Mass / Volume

Mass Measurement

• Tools needed: Beaker, scale
• Steps:
  1. Measure the mass of the empty beaker.
  2. Fill the beaker with the desired amount of water.
  3. Measure the mass of the filled beaker.
  4. Subtract the mass of the empty beaker from the mass of the filled beaker to get the mass of the water.
• Example:
  • Mass of filled beaker: 100 grams

Volume Measurement

• Tool needed: Graduated cylinder
• Example volume: 100 milliliters

Calculating Density

• Formula: Density = Mass / Volume
• Example Calculation:
  • Mass: 100 grams
  • Volume: 100 milliliters
  • Density: 100 grams / 100 milliliters = 1 gram/milliliter
• Water’s density: 1 gram/milliliter

Floating and Sinking

• Objects with density > 1 will sink in water.
• Objects with density < 1 will float in water.
• Examples:
  • Block with density 0.1 will float (10% below water line)
  • Block with density 0.5 will float (more of the block below water line)
  • Block with density 0.9 will float (most of the block below water line)
• Density determines the position of an object in water.
  • Converting density to percentage explains where the block will come to rest.

Ice and Density

• Ice floats because it expands upon freezing.
• No new atoms are added during freezing.
• Expansion causes atoms to be less tightly packed.
• Less density in ice than in liquid water causes ice to float.

Conclusion

• Key formula: Density = Mass / Volume
• Practice calculating density with different materials and objects.