What property of water does "specific weight" quantify?

• A. Volume
• B. Weight per unit volume
• C. Density
• D. Pressure

Answer: (B)

The property of water that "specific weight" quantifies is the weight per unit volume. Specific weight, often denoted as γ, is defined as the weight of a substance divided by its volume. This means it essentially describes how much mass is present in a given volume of water, taking into account the effect of gravity on that mass.

This is crucial in various engineering applications where understanding the buoyant forces and pressures of fluids is necessary. For instance, when designing structures that interact with water, such as bridges over rivers or foundations in coastal areas, engineers need to accurately consider the specific weight to assess stability and safety under different load conditions.

While density is related to specific weight—since density is mass per unit volume and specific weight includes gravitational acceleration in its calculation—they are not the same. Pressure relates to force applied over an area, and volume is simply a measure of space occupied, which does not directly communicate the concept of weight in relation to volume. Thus, identifying specific weight as the weight per unit volume correctly captures its defining characteristic.