Question

The neutral axis of the cross section of a beam is that axis at which bending stresses

Answer 1

ρ is the radius of curvature of the beam at its neutral axis. From statics, a moment(i.e. pure bending) consists of equal and opposite forces. Therefore, the total amount of force across the cross sectionmust be 0. Therefore the first moment of the cross section about its neutral axismust be zero.

I hope I help you

please don't forget to follow me