Two equal drops of water are falling through air with a steady velocity v. If the drops coalesced, what will be the new velocity?

Explanation

From conservation of mass.
`(4)/(3)piR^(3)xxrho=(4)/(3)pir^(3)xx rho+(4)/(3)pir^(3)xxrho`
`or R=(2^((1)/(3)))r and v_(t)alpha r^(2)" (stokes law)"`
`(v^(1))/(v)=(R^(2))/(r^(2))=2^(2//3)" "therefore v^(1)=2^(2//3)v.`