private float computeDeceleration(float friction) {
        return SensorManager.GRAVITY_EARTH   // g (m/s^2)
                      * 39.37f               // inch/meter
                      * mPpi                 // pixels per inch
                      * friction;
    }
The amount of friction applied to flings. The default value
is {@link android.view.ViewConfiguration#getScrollFriction}.

@param friction A scalar dimension-less value representing the coefficient of
        friction.
menudrawer/src/net/simonvt/menudrawer/Scroller.java