How much force does it require to break a bone?

Hey,

I've been tasked with making a question in Physics, and wanted to know how much force (Newtons) is required to break a bone. I'd prefer the ankle, but if you don't know that, any bone that would make sense to land on after a fall from a roof if fine too.

Thanks,

gogojakeo

Reply 1

Stonebridge

13

Original post by gogojakeo

Hey,

I've been tasked with making a question in Physics, and wanted to know how much force (Newtons) is required to break a bone. I'd prefer the ankle, but if you don't know that, any bone that would make sense to land on after a fall from a roof if fine too.

Thanks,

gogojakeo

You should be thinking of stress (F/A) rather than force, as the amount of force would depend on the thickness of the bone and hence the cross section area.
Bone would have a so-called "breaking stress" value. This will, in conjunction with the cross section, give you the breaking force.

Reply 2

Joinedup

20

Original post by gogojakeo

Hey,

I've been tasked with making a question in Physics, and wanted to know how much force (Newtons) is required to break a bone. I'd prefer the ankle, but if you don't know that, any bone that would make sense to land on after a fall from a roof if fine too.

Thanks,

gogojakeo

as luck would have it I broke my tibia a couple of years ago when I turned my ankle over playing sport.

well the strength of bone according to wikipedia is

compressive strength of about 170 MPa (1800 kgf/cm²),[3] poor tensile strength of 104–121 MPa, and a very low shear stress strength (51.6 MPa)

http://en.wikipedia.org/wiki/Bone#Mechanical

you'll need to get some values for the cross sectional area of bones to work out the maximum force they can stand - probably work this out from diameter or circumfernce in some publicly available source e.g. http://www.jstor.org/stable/658462?seq=4#page_scan_tab_contents

Reply 3

Phichi

11

This reminds of my school day in Physics. My teacher was always a cynical grumpy bah humbug man. I used to love spinning round on his blue 'spinney chair', so one day he decided how fast he'd need to spin me so that my legs would effectively break. Turns out, it wasn't really a viable option.