Test: Shear Force & Bending Moment - 1 - Mechanical Engineering MCQ

Reaction generated at fixed end would be same as end applied load.

At any x-section of a beam, the shear force ‘F' is the algebraic sum of all the lateral components of the forces acting on either side of the x-section.

Bending moment is the algebraic sum of the moments about an x-section of all the forces acting on either side of the section.

• When the beam is loaded in some arbitrary manner, the internal forces and moments are developed and they are termed as shear force and bending moments.
• Shear force at a section can be defined as the algebraic sum of all the lateral components of the forces acting on either side of the x - section.
• Bending moment at a section can be defined as the algebraic sum of the moments about that section of all the forces acting on either side of the section.

The rate of change of bending moment is equal to rate of shear force. The rate of change of shear force is equal to rate of loading.

This point is also the point of contra-fiexure and it will be zero at b = 2a.
So, answer is (d).

Contra-flexure = contra (opposite) + flexure (bending)

• We call point of contra-flexure at some location of any bending member like- beam where bending moment changes its sign along the length of the member for a particular load case.
• So, in Bending Moment Diagram, bending moment curve crosses the zero line at contra-flexure or simply, bending moment is zero at point of contra-flexure.
• It occurs in overhanging beam. In other beams also it can occur but in overhanging it will definitely will be there.