1. The problem statement, all variables and given/known data 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) 2. Relevant equations dA/dr = rate of evaporation, where A is surface area of water droplet...and radius of spherical water droplet. 3. 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?