1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Radius of Specimen from Flexural Strength

  1. Oct 31, 2013 #1
    1. The problem statement, all variables and given/known data

    A circular specimen of glass is loaded using the three-point bending method. Compute the minimum possible radius of the specimen without fracture, given that the applied load is 4000 N the flexural strength is 65 MPa, and the separation between load points is 35mm.

    2. Relevant equations

    Flexural Strength = (FL)/(pi*R3) where F is the load at fracture, L is the distance between support points (in mm), and R is the radius of the specimen.

    3. The attempt at a solution

    Flexural Strength = (FL)/(pi*R3)


    R = cube root of ((4000N)(0.035m)/(pi*6.5*10^7))
    R = 8.818 mm

    This is not one of the answers given. What am I doing wrong? The only thing I can think of is that the load given is NOT the fracture load, however I don't know how/from where to get that load.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted