What factors must be known when testing gravimetrically?

When testing gravimetrically, knowing the density and coefficient of expansion is essential because these factors directly influence the precision and accuracy of the measurement being taken. The density of a substance affects how much mass corresponds to a given volume, which is crucial when calculating mass from volume measurements or vice versa.

The coefficient of expansion becomes important because materials can expand or contract with changes in temperature. This means that if the temperature of the substance changes during the measurement, the density could also change, which would affect the results. For instance, many liquids experience a significant change in density with temperature variations, so knowing how much a particular liquid expands or contracts with temperature will help in achieving accurate mass measurements.

In contrast, while temperature and humidity are important in many measurement contexts, they aren’t the primary focus for gravimetric tests. Similarly, flow rate and pressure are critical in fluid dynamics or other test situations but do not pertain specifically to gravimetrics. Volume and weight are related but without considering density and thermal expansion, they lack the necessary context for providing accurate gravimetric measurements.