How is absolute pressure defined?

Absolute pressure is defined as the pressure measured relative to a perfect vacuum, or zero pressure. This means that absolute pressure measures the total pressure exerted on a system, taking into account the atmospheric pressure as well as any other pressure contributions that may be present. The significance of using absolute pressure is that it provides a consistent reference point for calculations, especially in scientific and engineering applications where variations in atmospheric pressure can affect results.

This contrasts with other forms of pressure measurement, such as gauge pressure, which is referenced from atmospheric pressure and can vary with changes in ambient conditions. Therefore, when dealing with absolute pressure, one has a clear framework that eliminates discrepancies caused by atmospheric variations, ensuring precision in calculations and assessments across different environments or conditions.