Question

I have some powder in a container with one side open. If I then compress it from that open side, does the powder evenly compress, or will the side closer to the opening (or furthest from the opening) compress more, and end up with a gradient of compression? For example, when tamping ground coffee in an espresso portafilter - is the coffee density even distributed through the portafilter, or will it be denser at the top or bottom?

And what factors (if any) affect this? Regarding individual particles - shape? size? texture? uniformity? compressibility (of each particle)?

Answer 1

In compression of powder such as coffee in a container, a density gradient may result from uneven tamping and variations in particle size, shape, texture, uniformity, and compressibility. Physics calculations use density and container dimensions to calculate necessary variables like volume or mass.

Step-by-step explanation:

When tamping powder, such as ground coffee, in a container with one open side, the compression is not necessarily even. The density gradient may vary, with the powder potentially being denser at the bottom or top depending on the tamping technique. Factors that affect this include the particle size, shape, texture, uniformity, and compressibility of each particle.

For instance, finer particles may lead to a more uniform density, whereas larger particles may not compact as evenly. Additionally, the uneven distribution of force during tamping can create a density gradient within the tamped material.

In physics-related calculations, the density of a liquid and the dimensions of a container are often used to determine volumes and masses. For example, to find the inside radius of a coffee mug with a uniform circular cross-section that holds 375 g of water to a depth of 7.50 cm, one can use the formula for the volume of a cylinder in conjunction with the known density of water.