My question is regarding the amount of force it would require to push
over a properly installed parking meter.  I am concerned about a
particular parking meter that is tipped to an angle of 20 degrees, and
it is my premise that this unit was never properly installed.

The assumptions of the meter and mounting as specified by town planning, are:
THE METER:
1)  The meter is manufactured by P.O.M., model N-APM, and set on a
Twin Adaptor #300-326.
I am assuming that the force is being applied to the side of the round
top part of the meter, so estimating this dimension above the pipe
post will be necessary to calculate the amount of moment.
THE POST:
2)  The post is 2? ID Galvanized Steel Pipe Post extending 37? up from
grade to the bottom of the meter.
3)  At grade there will be a depth of 4? of topsoil covering a concrete footing.
4)  The concrete footing begins 4?below grade and the steel pipe post
is embedded into the concrete to a depth of 12?.
THE FOOTING:
5)  The dimensions of the concrete footing are 14? in diameter, and
3?2? deep, below the 4? layer of top soil, requiring that a footing
hole be dug a total of 3?6?deep.
6)  The footing will be made of 3000 PSI, concrete.
I have already calculated that the volume of this cylinder of concrete
is 0.125 yards^3 and has a weight of 451.8 lbs, based on a cured
weight of concrete at 3600 lbs./ yard^3.  You can recheck these
calculations.

When applying this unknown amount of force there are several things
that could happen.
1)   The meter could break off the top of the post.  I guess this to
be very unlikely.
2)   The steel post could bend or break at its base.  I think that
this is what will happen.
3)   The steel post could break out of the cement footing.  I think
this is unlikely.
4)   The entire cement footing could shift in the earth allowing the meter to tip.

An assumption to be made is about the ?typical? earth here in Western
MA.  I do not know how to specify this.  Please tell me whatever
assumption is made.

ANSWERS REQUESTED:
1)  Where will the system fail and how?  The meter?  The pipe?  The
footing?  A combination of these parts?
2)  What would be the amount of force needed to bend the steel post to
an angle of 20 degrees?
3)  What would be the amount of force needed to shift the cement
footing in the earth so that the resulting angle of the meter would
shift to 20 degrees?
4)  If the cement footing is calculated to break, how much force would
this require?
5)  Depending on which parts, or what combination of parts, are
calculated to fail, how much force will be required to tip the meter
to angle of 20 degrees from vertical?

Please provide how you calculated the answers.

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Clarification of Question by sapien128-ga on 04 Jan 2006 10:24 PST

I wrote that I needed the answer by the end of 1/2/06, but I will
leave the question posted until the end of the month and be interested
in the reply.

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Clarification of Question by sapien128-ga on 06 Jan 2006 21:17 PST

I am sorry that I wasn't more clear in my question.  The height of the
post that supports the meter is 37" from grade up to the bottom of the
meter.  The total height of the meter is 24"  The distance from the
bottom of the meter to the large round part of the meter head, where I
expect that the force would have been applied, is 20".  The total
distance from grade to the location where the force was applied is a
total of 37" + 20" = 57".

I see this more as a civil engineering problem than a question of
physics.  If I knew the force x 57" I could easily calculate the
amount of moment this would generate.  What I don't know how to do is
figure out how much force the meter will withstand, or where it will
fail when this force is exceeded.

Will the meter head break off?  Will the post bend, and if so where? 
Will the post break out of the 14" diameter cement footing?  Will the
footing shift in the earth?  Or will some combination of these things
occur for the meter to be shifted to a 20 degree angle from vertical?

My guess is that the pipe will bend at the footing and that it will
require in excess of 1000 pounds of force for this to happen.  I don't
think that the footing will break or shift in the earth but I do not
know enough about the fracture characteristics of cement or about soil
science to calculate this.

Please feel free to ask for any other clarifications needed.  Thanks.

Where is the force acting?  At the top of the meter?  Somewhere along
the post?  The average car bumper height (like 16" or so from the
ground)?

The location of this unknown force is what matters most.

The solution will require calculating the moment applied to the post's
foundation.  Since a moment is a Force x Distance, we'll need to know
exactly where that force is being applied (measured from the ground).