"Lew Hodgett" wrote in message
ink.net...
Bruce wrote:

I do chin ups from a bar that hangs from 1 eye bolt in the ceiling and
I
weigh around 225. It's in a 2X6 though. I'd be much more worried about
the 2X4 breaking than the eye bolt coming out.
snip

The moment of inertia for a rectangle is: (b*h^3)/12 where b=base &
h=height.

The moment of inertia is a measure of a beam's resistance to bending.

Do the math and you will find a 2x6 rectangle has a moment inertia of 4.5
times that of a 2x4 rectangle, thus 4.5 times stronger in resisting
bending.

Lew

Close. As you state, given a constant value for "b", moment of inertia is
proportional to the cube of the height. (5.5/3.5)^3=3.9, not 4.5. If you
meant a literal 2x6 vs. a 2x4 rectangular cross-section, the ratio would be
3.4.

todd