Randall D. Knight — Dynamics I: Motion Along a Line: Problem 68

Electrostatic precipitation is used to remove small particulates from the emissions of coal-fired power plants. The particles are given a small electric charge that causes them to move toward a large, oppositely charged plate where they stick. A typical particulate is a 1.0-μm-diameter sphere with a density of 1300 kg/m3. With what speed in mm/s does it drift toward the collector plate if the electric force is 1.2 × 10-12 N? Gravity can be neglected because the electric force is much larger. The viscosity of air in the 200°C exhaust is 2.5 × 10-5 Pa s.