How to calculate for a lever?

[daviedixon]

Hi,

I am trying to find out how to calculate for what I can only describe as a lever?

I have a free standing force sensing pole at a height of 600mm that requires 20lbs of force at the top to send a signal.

I want to build a base around the bottom of the pole to hold it upright.

How would I work out the required dimensions of the base to ensure the 20lb force would not tip the pole over?

Kind regards

Dave.

[Kelly_Bramble]

?




see:


http://www.engineersedge.com/calcula...calculator.htm

[daviedixon]

Thanks Kelly but not sure that it was I am looking for though, it's probably my failure to understand the results.

Taking the analogy of a flag pole that is not to be buried in the ground rather, I am looking to make a freestanding baseplate

If the pole is 600mm high how do I calculate the correct dimensions of the baseplate to stop the pole from tipping over if 20lbs of force is applied at the top?

Is it as simple as saying that regardless the size of the baseplate so long as it weighs more than 20lbs then it will counteract a 20lb force at a height of 600mm?

Kind regards

Dave.

[Kelly_Bramble]

If the radius of the base is r, then the torque due to gravity when you just begin tipping the lamp will be Γ=mgr.

The other question for stability is - how far can things move before they become unstable? For this, we need to know the height of the center of mass above the support - the higher the c.o.m., the sooner the object will tip by itself.



As soon as the pole begins to tilt, the available torque decreases; in fact, you can see from the diagram that r′, the reduced arm of the weight of the pole, is

r′=rcosθ−hsinθ

This will become zero when tanθ=rh tan⁡θ=rh.