Scaling - The Physics of making my mind go crazy.

[37fox]

Hi guys,

I'm a high school student at a private high school in the LA county called Bishop Amat Memorial. I'm currently in Honors Physics, so far I've been have a smooth and fine time until my teacher hit us with a project concerning scaling...

His philsophy of teaching for this project is, "Find out how to do it, and teach yourselves." I can understand why and what he's trying to get at by saying that, but it's been really tough on me.

Well to the point, if someone can at least HINT me or really help me out on this question, I think i'll be fine for the rest of the whole entire project,
This is the question that stumps me, even after doing about 2 solid hours of hopeless and tiresome research on the net...

Measure the circumference from one of your ankles. Make the rough approximation that your ankle is entirely bone. Determine the weight per unit cross sectional area on your ankle bone.
Once you find this out, an elephant has a foot circumference of 52 inches (130 cm) and a weight of 9300 (4.1 x 10^4 N). Determine the weight per unit cross sectional area on the elephant's leg bone, assuming that hte foot is mostly bone.

The rest of the project conerns the movie Godzilla, but I won't get into that.

I have an idea what a unit cross sectional area is, it is the samething as if a plane would go through a cyclinder is it not? If I have the wrong idea, please correct me. If possible, please explain "the weight per unit cross sectional area" to clarify my confusion.

Please help me,

a confused and tiresome student.

 

[Danger]

Your assesment is essentially correct, and welcome to PF. All that you need to do is figure out the cross-sectional area of the bone (pi*r^2), multiply it by the number of legs, and divide the weight by that number. That will give you the weight per leg.
This is also the basis for scientists laughing at schlock SF movies like 'The Attack of the 50 Foot Woman'. The structural support of a column (eg. leg) increases as the square of the size; the weight increases as the cube. Above a particular growth factor, the legs can no longer support the body.

edit: By the bye, the reason that elephants can't jump is that they don't have the leg structure for it. Their limbs are adapted for severe weight-bearing.

 

[37fox]

I'm I to divide the weight of my whole body? or an approximated weight of my leg?

 

[Janus]

I'm I to divide the weight of my whole body? or an approximated weight of my leg?

The weight of your whole body, as this is the weight that your ankles support while you are standing.