Bind multiple objects to slide event?

Bind multiple objects to slide event?

I have several objects on a page I want to connect to a slider. Imagine if you will:

Slider 1: "#design-speed-slider"
Slider 2: "#actual-speed-slider"

Box 1: "#protection-zone"
Box 2: "#dilemma-zone"

Box 2's size and position are determined solely by the value of Slider 2, but Box 1's size and position are determined by the values of both Slider 1 and Slider 2.

In the slide event of Slider 1, I try referencing the value of Slider 2:

var designSpeedMPH = $("design-speed-slider").slider("value");

But this isn't working.

Would it be better to create a method on the boxes themselves that calculates their size and position? How would I bind that to the sliders?