College Physics III – Thermodynamics, Electricity, and Magnetism
Definition
The density of water is the mass per unit volume of water, typically measured in kilograms per cubic meter (kg/m³). It varies with temperature and pressure, being approximately 1000 kg/m³ at standard conditions (4°C and 1 atm).
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The density of water reaches its maximum value at 4°C, which is approximately 1000 kg/m³.
As water is heated above 4°C or cooled below this temperature, its density decreases due to thermal expansion.
Ice has a lower density than liquid water, which is why it floats.
The anomalous expansion of water between 0°C and 4°C prevents bodies of water from freezing solid from the bottom up.
In thermodynamic calculations, variations in the density of water with temperature can significantly impact results involving buoyancy and fluid dynamics.
Review Questions
At what temperature does water reach its maximum density?
Why does ice float on liquid water?
How does the density of water change when it is heated from just above freezing to room temperature?
Related terms
Thermal Expansion: The tendency of matter to change its shape, area, and volume in response to a change in temperature.
Buoyancy: A force exerted by a fluid that opposes an object's weight; influenced by the fluid's density.
Specific Heat Capacity: \(c_p\) The amount of heat required to raise the temperature of one kilogram of a substance by one degree Celsius.