Sorting (hydraulic) classifiers that use differential settling separate particles primarily based on differences in which property?

Introduction / Context:
Hydraulic classifiers segregate particles in a fluid under gravity by exploiting differences in settling behavior. The governing property is the terminal settling velocity, which depends on size, density, and shape.

Given Data / Assumptions:

• Particles settle in a fluid column.
• Steady, laminar-to-turbulent settling as applicable.

Concept / Approach:
Terminal velocity v_t encapsulates the combined effects of particle size and density in a given fluid. Classifiers set operating conditions so that particles with higher v_t report differently than those with lower v_t, achieving separation.

Step-by-Step Solution:
Note that “size” and “density” influence v_t.Recognize the device acts on the resulting v_t differences directly.Choose “Terminal velocities.”

Verification / Alternative check:
Design correlations (e.g., Stokes or Newton regimes) predict v_t; classifiers are tuned to these predictions.

Why Other Options Are Wrong:
Size or density alone is incomplete; v_t captures both.Surface charge is relevant to electrostatic separation, not hydraulic classifiers.

Common Pitfalls:
Treating size-only classification; in fluids, density differences can override size alone.

Final Answer:
Terminal velocities