What is water equivalent?

Water equivalent is a measure used to express the heat capacity of a material in terms of the equivalent mass of water that would absorb the same amount of heat. It is calculated by determining how much heat is required to change the temperature of the material and then comparing that to the heat needed to change the temperature of a specific mass of water. This concept is useful in thermodynamics and calorimetry for simplifying calculations involving heat transfer. Essentially, it allows for the comparison of different substances in terms of their thermal properties relative to water.