Noname 123 What you are talking about is a dynamic lever, like a whip, in which the lenth of the output arm changes over time. Essentually it a first class lever.

I agree that the flexible whip could be defined as dynamic, but I mean something quite different. Can I ask this question:- Q: We have equal masses equidistant on a beam, either side of a common pivot point. That arrangement is said to be in a state of perfect balance. Because the centre of mass = centre of gravity in all revolute positions about the pivot point, the system is said to be gravity equalised, meaning PE is constant at all times. Agree? Now, do you, mathematical, foresee, a situation whereby we can remove a mass from that balanced beam, yet still maintain perfect countenance of the remaining supported mass without any intervention to alter the radial position of the remaining mass on the beam ? No masses are located at the pivot point.

Noname 123 In a word,no. However, we cannot just assume the comass is at the same point as the cograv.But regardless, the system you are describing is still a first class lever. If the pivot point is static the revoving a mass from the beam would take it out of equilibrium producing a torque resultin rotation. Basically the same as a pully wheel, which is , well, a first class lever.

Ok that answer is actually good for me as it means I've designed something noteworthy. If you private message me on My page? I'll show you how its done :)