N identical spherical drops of radius r and terminal speed v coalesce into one drop in the same viscous medium. Assuming Stokes' law remains valid, which statements are correct?
Select all that apply

Question

N identical spherical drops of radius r and terminal speed v coalesce into one drop in the same viscous medium. Assuming Stokes' law remains valid, which statements are correct?

G1 Physics · Accepted Answer

Volume conservation gives R³ = Nr³, so R = r∛N. Because vₜ ∝ r², we obtain v(new) = v(R/r)² = v(∛N)². For N = 8, ∛8 = 2, so v(new) = 4v. For N = 27, ∛27 = 3, so v(new) = 9v. Therefore all four statements are correct.