Hi, I am currently doing a project to design a lamp and am really interested in using physics to gain a perfectly balanced design. I have come across this diagram... http://upload.wikimedia.org/wikipedia/en/a/a7/Lamp_2_counter_weight.PNG I just want to clarify a couple of things before I go ahead and produce it! Apologies if these are stupid questions but it is a while since I did any physics. 1. I can turn these into any numbers as long as the ratio says the same right? E.g. Half the weights. 2. The the pivot points need to remain exactly there in order to balance or does another option exist? By this I mean the lamp head is moveable in almost any direction, but with the layout of the arms in a different way? 3. The measurements on the diagram (10,20 etc.) seem to show the measurement to the centre point of the weights... Is this what I need to measure to (the centre of mass of the weight?) or can the weights differ in dimension as long as the mass remains the same? 4. Imagine a curtain pole (the arm) with a screw (the weight) half screwed into the end... Where would I measure 10,20 lengths to? The end of the pole or up to the start of the screw? Thank you so much for this. James.