Lever with offset pivot problem

  • #1

Homework Statement

I have a situation a shown in the diagram below. A lever with a gas compression spring opposing it's turning. I want to find the force acting on the spring, F1, for a given inital force @ F0.

[PLAIN]http://img18.imageshack.us/img18/9830/lever01.png [Broken]

Homework Equations

The Attempt at a Solution

I don't think this is a trivial lever problem but I may be wrong?
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  • #2
Welcome to PF.

You're right. It's not trivial.

How do you plan to solve it?
  • #3
I have reduced it to a static problem and am looking at the initial configuration as drawn above, before any movement.

In this situation I believe that F1 can be worked out by introducing an imaginary lever, as shown below and balancing the moments i.e.

(F0)(5x) = (F1)(y)

where y can be found by trigonometry using similar triangles.

However if we revert the problem back to a dynamic one, the length y will change as the system turn and the spring compresses, so for a constant force F0, F1 will vary. However I think you could plot this out over a certain turning angle, by just selecting a range of angles and calculating y for that configuration and thus F1.

I appreciate any comments :smile:

[PLAIN]http://img839.imageshack.us/img839/8334/lever02.png [Broken]
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