Question

A cantilever beam is 2 m long. The cross-section of the beam is hollow square, with external sides 60 mm and the internal side is such that $I=6\times {10}^{5}m{m}^4$. If the safe bending stress for the material is $100N/m{m}^2$, the safe concentrated load at the free end would be

• A. 400 N
• B. 500 N
• C. 600 N
• D. 1000 N

Answer 1

The correct option is D 1000 N


The bending moment
at end A = 2WNm

Maximum bending stress,

$f=\frac{2W\times {10}^3\times 30}{6\times {10}^5}=100$

$\therefore$ W = 1000 N