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## Homework Statement

A freely falling water drop continually evaporates. Assuming that the net momentum carried away by the vapor vanishes, calculate the velocity of the drop as a function of time. (Assume that the rate of evaporation varies as the surface area)[/B]

## Homework Equations

dA/dr = rate of evaporation, where A is surface area of water droplet...and radius of spherical water droplet.

## The Attempt at a Solution

dA/dr= d(πr^2)/dr=2πr

Cant understand what "net momentum carried away by the vapor vanishes" means...cud it be that there r no drag forces the the vapor drop...

. Then how do I find the vel. Of the drop?