A stream of water falling down a faucet will experience the force of gravity which makes it accelerate. As its velocity increase, in order to conserve its volume, the stream will get narrower, as it travels down. My question is; is that the only reason why the stream gets narrower when it is falling from a faucet?

 

Water molecules can form relatively strong hydrogen bonds and also the stream experiences air resistance. Don't these forces also contribute to the stream of water getting narrower as it flows down?

 

Thanks.

The hydrogen bonds help keep the stream consolidated as it accelerates, and the moving stream does produce a "parasitic drag", which would hold the stream back, but it is a relatively minor force.

Edited May 28, 201213 yr by ewmon

Surface tension will also tend to narrow it.

Surface tension will also tend to narrow it.

I think that a short video I shot illustrates the effect of surface tension on water flow. It is a slow motion video of water flowing in a fountain. See: