Avolcanic plume puts ash into the atmosphere to altitude of 1m. the characteristic ash particle is a sphere with a diameter of 40 um and has a density of 1000 kg/m^3. consider a single ash particle in isolation that is travelling vertically at its terminal velocity (i. e. no acceleration). assume the density and kinematic viscosity of the air are independent of altitude and is given ,ρ=07kg/m3 and v= 1.5 x 10° m2/s. the drag coefficient is given by stokes' relation: cd =24/re. which of the following answers is closest to the length of time it takes for the particle to settle to the ground? a) 2 hours b) 53 hours c) 33 hours d) 21 hours