Dumbbell Counter Weight Calculation

[Fluxite]

Homework Statement

Hi all, First post so please go easy

I am designing a Dumbbell support that presents the Dumbbell to the user in the correct exercise starting position (1. Shown on the image.) . The problem I am facing is the counter balance to the support. The Dumbbells range from 15kg-90kg and I assume the counterbalance has to match. My question is would it be possible to use an adjustable support (2. Shown on the image.) and what calculations would I need to calculate this?

Homework Equations

I would assume I need counter balance and pivot equations but I have no prior knowledge of this.

The Attempt at a Solution

Unsure, as stated no previous knowledge.

Any information or help would be greatly received,

Thank you in advance,
Samuel

 

[gneill]

You'll want to investigate the concepts of moment arm, torque.