https://api.flutter.dev/flutter/widgets/BouncingScrollPhysics/frictionFactor.html

This factor starts at 0.52 and progressively becomes harder to overscroll as more of the area past the edge is dragged in (represented by an increasing overscrollFraction which starts at 0 when there is no overscroll).

However, the bigger the overscrollFraction parameter is, the less the returned friction

This codesample will print out decreasing values

import 'dart:math' as math;

void main() {
  double frictionFactor(double overscrollFraction) => 0.52 * math.pow(1 - overscrollFraction, 2);
  for (double i = 0; i < 1; i += 0.01) {
    print(frictionFactor(i));
  }
}