# 4 Point Reaction

1. Jan 21, 2010

### larocket83

I'm pretty rusty on my statics. I'm wondering how I could determine the reaction at four points arranged in a rectangle, with a force acting in the x direction at a distance away from the plate I have shown in this graphic. I seem to remember the term statically indeterminate, I think this applies, but is there any way to figure out the forces that each of these corners see? (Assume the points are fixed to the floor.)

2. Jan 21, 2010

### tiny-tim

Welcome to PF!

Hi larocket83! Welcome to PF!
You're right, it is statically indeterminate … you can calculate the forces for a table on three legs, but not on four legs (basically because if you take one leg away, the table will still stand up … or, mathematically, because you have more unknowns than equations).

Of course, you can solve it, but you need one more equation …

in this case, you need to know how bendy the table is.

3. Jan 21, 2010

### frustr8photon

wow, this is incredibly awesome. if the bendy-ness were given, what kind of quantity would that come as?

also, are tensors used to solve this problem?

4. Jan 21, 2010

### tiny-tim

A modulus … see http://en.wikipedia.org/wiki/Modulus_of_elasticity" [Broken]
Maybe … bendy-ness depends on lots of things (it's flexible ).

Last edited by a moderator: May 4, 2017