# Engineering Mechanics Questions and Answers – Internal Forces Developed in Structural Members – 1

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This set of Engineering Mechanics Multiple Choice Questions & Answers (MCQs) focuses on ” Internal Forces Developed in Structural Members – 1″.

1. The determination of the internal loading is usually done so as to _________________
a) Break the beam
b) Know the length
c) Know the diameter
d) Design the beam

Explanation: The determination of the internal forces in the beam is done so as to design the beams as in the application purpose the beams will be subjected to many loads. This will help us to make the beam properly. And also this will ensure that the beams will not break after the loading is done on them.

a) Method of sections
b) Method of area
c) Method of line
d) Method of volume

Explanation: The determination of the internal forces is done by various methods among which the method of section is the one. Also, we have method of joints, which is done so as to determine the internal forces which are being developed in the trusses or the frames. This is done as to design them.

3. In the method of sections we probably use the joints and take out the forces in the beams.
a) True
b) False

Explanation: In method of sections the determination of the forces is done over the trusses or the beams. It is not done on the joints. But yes the joints are used as the forces acting on the joints are used in the calculations. This is again used for the designing of the beams.

4. The ____________ forces are used for the making of the free body diagram of the beams so as to apply the method of sections.
a) Internal rotational
b) Couple rotational
c) Translational
d) External

Explanation: The free body diagram is using the external forces which are acting on the beam as the main purpose is to design the beam. Design so as to withstand the loads which are going to be added to the beams. Thus the loads which are being added externally are being used in the free body diagrams.

5. Rotational moments are not counted in the free body diagrams and the evaluation of the internal forces by the method of sections.
a) True
b) False

Explanation: In the method of sections the determination of the forces is done over the trusses or the beams. It is not done on the joints. But yes the joints are used as the forces acting on the joints are used in the calculations. This is again used for the designing of the beams.

6. The force acting perpendicular to the beam is called _______________ force.
a) Perpendicular
b) Orthogonal
c) Normal
d) Distortion

Explanation: The forces which are acting perpendicular to the body of the beams are called as the normal forces. These are the forces which are supporting the beam. These forces are being calculated by the help of equilibrium equations. Thus the forces which are perpendicular to the surface are the normal forces.

7. The force acting parallel/tangential to the beam is called _______________ force.
a) Perpendicular
b) Orthogonal
c) Shear
d) Distortion

Explanation: The forces which are acting tangentially to the body of the beams are called as the shear forces. These are the forces which are giving moment to the beams. These forces are being calculated by the help of equilibrium equations. Thus the forces which are parallel to the surface are the shear forces.

8. The couple moment produced in the beams are called as ____________________
a) Moment of distance
b) Moment of line
c) Moment of bending
d) Bending moment

Explanation: The forces are making the body tend to rotate. This is in general making the body rotate or make generate the moment in the beams. This moment is the same thing as the couple moment. But in beams it is referred as bending moment. And is again used for the designing of beams.

9. The force components prevent the beam from which of the following process?
a) Relative translation
b) Relative rotation
c) Relative transformation
d) Relative collapse

Explanation: The force components are the forces which are the ones which prevent the beam from relative translation. This means that the shearing generated will be held strongly by the help of the forces generated. The main motto is to make the beam stable and don’t allow the relative translation occur.

10. The couple moment prevents the beam from which of the following process?
a) Relative translation
b) Relative rotation
c) Relative transformation
d) Relative collapse

Explanation: The couple moments are the moments which are the ones which prevent the beam from relative rotation. This means that the rotation generated will be held strongly by the help of the opposite moments generated. The main motto is to make the beam stable and don’t allow the relative rotation to occur.

11. According to the _________ law of Newton the loadings at the sections must act opposite to the forces applied.
a) First
b) Second
c) Third
d) Fourth

Explanation: As the law state that there is always a reaction to every action applied. Thus if the forces are applied at the section of the beams, i.e. the external forces than there must be reactive forces. And these reactive forces act in opposite directions of the forces which are being applied externally.

12. For the determination of the forces at the supports which part is to be considered in the calculations?
a) The one having one unknown and two known forces
b) The one having two unknown and two known forces
c) The one having three unknown and two known forces
d) The one having two unknown and one known forces

Explanation: The determination is usually done in this manner only. The selection is done as by selecting the one having one unknown and two known forces. This will ensure that the unknown value will be found. And also we have less number of unknowns which are needed to be found.

13. What is not the condition for the equilibrium in the beams if considered a section on which the method of sections is applied?
a) ∑Fx=0
b) ∑Fy=0
c) ∑Fz=0
d) ∑F≠0

Explanation: For the equilibrium in beams by considering any of the axis we have all the conditions true as, ∑Fx=0, ∑Fy=0 and ∑Fz=0. Also, we have the summation of the forces equal to zero. Which is not a non-zero value. Thus the conditions for the equilibrium of the beams.

14. Determine the moment at the point R of the beam shown. a) 225Nm
b) 25Nm
c) 22Nm
d) 23Nm

Explanation: The loading acting upward is considered to be positive. This is done as to decrease the time used for the calculations. If the method of sections is being applied at the complex sections for the determination of the unknown forces, much time is required for it. Thus the main motto is to make the calculations easy and make the less use of time.

15. Determine the normal force generated. a) 0N
b) 25N
c) 22N
d) 23N 