title: Handling Velocity/Inertia on Dragging
body: <p>I've built a vertical sliderish thing in my web application with the support of mouse and touch dragging events by Hammer.js. At the end of the drag (when user releases mouse button or takes his finger off the screen, a.k.a <code>dragend</code>event), if the one above is closer to middle, it gets moved to the middle and vice versa. </p>
  
  <p>The thing is, when dragend event is triggered at 48% when user drags the mouse from down to up (which means the one above will get moved to middle) if the velocity is high enough, the one below should get moved to middle. How to calculate if the velocity is high enough?</p>