Question

Two drops of same radius are falling through air with steady velocity of `v" "cm//s`. If the two drops coalesce, what would be the terminal velocity ?
A. `4v`
B. `(4)^(1//3)v`
C. `2v`
D. `64v`

Answer 1

Correct Answer - B
`V_("Big")=2V_("Small")" "impliesR_(B)=2^(1//3)R_(S)`
`v_(T)=(2)/(9)(piR^(2)(rho-sigma)g)/(eta)=v_(T)propR^(2)" "impliesv_(T(B))=2^(2//3)v_(T(S))impliesv_(T(B))=4^(1//3)v_(T(S))`