Reisen
Oct22-04, 02:31 AM
I've got a homework problem that starts like so:
Assume that Young's Modulus is 1.5 x 10^10 N/m^2 for bone and that the bone will fracture if stress greater than 1.5 x 10^8 N/m^2 is imposed on it.
If the effective diameter of the bone is 2.5cm, what is the maximum force that can be imposed on it (before breaking, I assume)
Here's what I've done:
A=(.0125m)2π = 4.91*10^-4 m^2
1.5*10^8 N/m^2 = F/A
1.5*10^8 N/m^2 = F/(4.91*10-4m^2)
3.055*10^11 = F
Problem is, that's a completely off-the-wall figure to get. It equates to about 68 billion pounds, and I know that bone would break well before then. I assume that the Young's Modulus provided isn't perfect, but couldn't be that far off.
So where did I go wrong?
Thanks in advance,
-Reisen
Edit: I got it, finally. Apparently, Algebra > Me :cry:
Assume that Young's Modulus is 1.5 x 10^10 N/m^2 for bone and that the bone will fracture if stress greater than 1.5 x 10^8 N/m^2 is imposed on it.
If the effective diameter of the bone is 2.5cm, what is the maximum force that can be imposed on it (before breaking, I assume)
Here's what I've done:
A=(.0125m)2π = 4.91*10^-4 m^2
1.5*10^8 N/m^2 = F/A
1.5*10^8 N/m^2 = F/(4.91*10-4m^2)
3.055*10^11 = F
Problem is, that's a completely off-the-wall figure to get. It equates to about 68 billion pounds, and I know that bone would break well before then. I assume that the Young's Modulus provided isn't perfect, but couldn't be that far off.
So where did I go wrong?
Thanks in advance,
-Reisen
Edit: I got it, finally. Apparently, Algebra > Me :cry: