Question

A small pollutant particle falls to the ground through the air at rest with a speed limit of 0.3 mm / s. The particle has a mass of 10 ^ -10 g and the drag force is of the form bv. What is the value of b?

Answer 1

Answer:

3.3×10⁻⁹ kg/s

Explanation:

There are two forces on the particle: weight force pulling down and drag force pushing up.  At terminal velocity, the speed is constant, so the acceleration is zero.

∑F = ma

bv − mg = 0

b = mg / v

b = (10⁻¹³ kg) (9.8 m/s²) / (3×10⁻⁴ m/s)

b = 3.3×10⁻⁹ kg/s