1. The problem statement, all variables and given/known data A. Explain why a stream of water coming out of a faucet gradually grows more and more narrow as you descend in height. B. At a certain height below the faucet, the area of the slice of water is A0 and its speed of descent is V0. Calculate the area of the slice of water positioned h below the A0 slice. C. What is the shape of the curve describing the envelope of the liquid (I think I'm asked for the 2d envelope, rather than the 3d envelope. 2. Relevant equations Well, this appeared in the kinematics part of my textbook, so any hydrodynamic considerations are most likely irrelevant. More notably, this appears among a group of questions that solely deal with ballistic trajectories*. 3. The attempt at a solution *Haha, just as I wrote that line, a possible answer to A popped into my mind: The individual water molecules have overall random velocity vectors (Though almost all of them point downwards to an extent because of the external water pressure, correct?). Though assuming they all have the same average magnitude is safe, given the incredible number of particles, this also means they are pointed in different directions. At the upper slices, we have all sorts of velocity vectors, but the molecules in the lower slices, got there faster because they had a more significant initial velocity downwards, so they got there faster. The most narrow part of the stream is consists of the 'fastest downward' molecules, with each slice being comprised of water molecules of a certain initial downward component to their velocity. Is this the correct explanation? This makes sense on its own, but doesn't amount to a hill of beans when I try to approach B with it. A nudge in the right direction would be greatly appreciated. EDIT: Ah, Gotta love the Similar Threads for: Narrowing stream of water I think I'll be all set from here on out. Sorry for the thread clutter.