1. Can anyone please explain in detail How a Vortex if formed. I mean what are the reasons and physical phenomena that cause the water entering a bath tub sink to gain a CIRCULAR ROTATIONAL motion and form a Vortex. How do the water molecules otherwise travelling straight towards the sink suddenly form a circular path of motion. What I want to understand is that how does this TURNING happen. And also explain about the pressure differences created and velocities in the vortex. 2. And why does a bullet gain more velocity when it is spinned along the grooves made inside the barrel, i mean how does the velocity increase because of the rotation. Please try to be detailed and elaborate it will help to understand better. Expecting a lot from this forum and experts here. This is my very first question here guys , so just help me out.