The moment at a hinge will be:
Try it first: pick an option, then read the explanation.
Correct answer: B. Zero
Asked in SSC JE 25/01/2018 (Morning)
Detailed Explanation
The moment of a force about a point is the force times its perpendicular distance from that point. A hinge (pin) joint lets the connected parts rotate freely relative to each other.
Why “Zero” Is Correct
Since a frictionless hinge offers no resistance to rotation, it can pass on forces (horizontal and vertical) but not a moment. So the bending moment at a hinge — whether a hinged support or an internal hinge — is zero. This fact supplies an extra equation, e.g. in three-hinged arches.
Why the Other Options Are Wrong
- A. Infinity: An infinite moment is physically impossible at any real joint.
- C. Depends upon acting forces: Whatever the loads, a frictionless hinge cannot carry moment.
- D. None of these: Zero is the correct answer and is listed.
Key Point
Bending moment at a hinge (support or internal) = 0.
Key Concepts for Students
- Simply supported beam: BM is zero at both supports.
- Each internal hinge adds one equation (ΣM = 0 about the hinge for one side).
- Moment of a force = F × perpendicular distance (N·m).
Practice more: this is question 10 in Moment MCQs – Part 1. Try the whole set and check every answer instantly.