Page scroll kinetic should depend on the actual scroll

The speed how the scrollable content moves, when using the page up/down functionality of the thumb, should vary depending on the actual amount of scroll animated. While when the content scrolls for an entire page the current duration of 1 second is fine, when the content scrolls for less than a page (ie. when the content is close to the minimum or maximum scroll) the duration should be smaller.
Given a minimum duration of 0.25 seconds, the formula to calculate the duration should look like:

var minDuration = 0.25;
var maxDuration = 1;
var duration = minDuration + (actual_scroll/page_scroll) * (maxDuration - minDuration);