Equilibrium of a Rigid Body topics include: Rigid body equilibrium conditions, two and three force members, free body diagrams, constraints and statical determinacy. A rigid body is in equilibrium when the sum of all forces acting on it is zero. The body must also be in translational and rotational equilibrium.  Here are some other conditions for a rigid body to be in equilibrium: The body's linear and angular acceleration are zero relative to an inertial frame of reference. The body is not changing its linear or angular momentum. The body is not moving because its forces and torques are... Show more

Equilibrium of a Rigid Body topics include: Rigid body equilibrium conditions, two and three force members, free body diagrams, constraints and statical determinacy.

A rigid body is in equilibrium when the sum of all forces acting on it is zero. The body must also be in translational and rotational equilibrium. 

Here are some other conditions for a rigid body to be in equilibrium:
The body's linear and angular acceleration are zero relative to an inertial frame of reference.
The body is not changing its linear or angular momentum.
The body is not moving because its forces and torques are balanced. 

A resting object is also in equilibrium because it has no rotation, and the sum of the torques exerted on it is zero.

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Engineering Mechanics Practice Test: Equilibrium of a Rigid Body

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25 Questions

1. What is partially constrained?

There will be more equations available for equilibrium than the reactive forcesThere will be equal equations available for equilibrium as the reactive forcesThe support reactions are opposite to each otherThere will be less equations available for equilibrium than the reactive forces

2. Determine the value of the q, parallel to the z axis. That is the point of intersection of the projections of the points A, B and C parallel to the xy plane. With the distance between the tri-section point and the points A, B and C be equal to 0.6m.

51.9m51.9cm5.19mm51.9mm

3. The net moment of the body is zero that means the distance between the force and the rotational axis is zero.

The first part of the statement is false and other part is trueThe first part of the statement is true and other part is falseThe first part of the statement is true and other part is true tooThe first part of the statement is false and other part is false too

4. The force and the couple can’t be simplified together as one is the cause and the other is the effect in free body diagrams.

The statement is correct and the reason given is also correctThe statement is wrong but the reason given is also correctThe statement is correct but the reason given is also wrongThe statement is wrong and the reason given is also wrong

5. Which of the following needs to zero for the perfect equilibrium?

∑F≠0, ∑M=0 and ∑θ = 0∑F=0, ∑M≠0 and ∑θ = 0∑F=0, ∑M=0 and ∑θ≠0∑F=0, ∑M=0 and ∑θ = 0

6. Which of the following statement for the three force system is true?

The forces are always in equilibriumThe forces are not always in the equilibriumThe moments are always in equilibriumThe moment need not be seen for the equilibrium, they are always in equilibrium

7. The shown here has a mass of 100kg. What is missing here in the diagram?

The moment of the force is not shownThe weight of the body is not shownThe body cant be held like thisThe body diagonal is not shown

8. Which of the following is correct?

The application of the conditions of the equilibrium of the body is valid throughoutThe application of the conditions of the equilibrium of the body is valid only if the forces are collinearThe application of the conditions of the equilibrium of the body is valid only if the forces are perpendicularThe application of the conditions of the equilibrium of the body is valid only if the forces are parallel

9. The system of the collinear and the parallel force in free body diagrams are simplified as _________

The simplification is usually done by not considering the directions of the bothThe simplification is done by considering the rotations onlyThe simplified collinear force system gives us a net force and the parallel force system gives us a simplified force, and then we add it vectoriallySuch simplification is not possible

10. Which of the following is correct?

The three force members doesn’t apply the moments to the bodyBoth the three and two force members apply the moments to the bodyOnly the two force members apply the moments to the bodyThe two force members doesn’t apply the moments to the body

11. If five forces are acting on the single particle and having an angle of 72˚ between each and are collinear, then:

The net force acting on the body is verticalThe net force acting on the body is zeroThe net force acting on the body is at an angle of 45The net force acting on the body is horizontal

12. The main moto of the free body diagrams is to:

To subtract the forces with the couples and take out the totalTo multiply the forces with the couples and take out the totalTo reduce the calculationTo add the forces with the couples and take out the total

13. The single pin, single bearing and single hinge resist _______

ForceCouple momentsInertiaBoth force and couple moments

14. If all the reactive forces are intersecting at the common point or pass through a common axis when _____________

The body is in equilibriumThe body is in deformationThe body is said to be improperly constrainedThe body is said to be achieve stability but no equilibrium

15. Determine the horizontal components of the reaction on the beam caused by the pin at Q.

268N28N68N288N

16. In 3D the body will be improperly constrained if the axis is intersected by the reaction forces.

The statement is right if there is ‘support reaction’The statement is wrongThe statement is rightThe statement is right if there is ‘2D’

17. The additional equations invented in the statically indeterminacy condition is solved by __________

Rotational equationsDeformation conditions at the point of supportsTranslation equationsLinear rotation equations

18. For the conditions of the equilibrium of the body, i.e. the rigid body only the external forces defines the equilibrium. And the support reactions only adds the rotation part of the body.

The first part of the statement is false and other part is false tooThe first part of the statement is true and other part is true tooThe first part of the statement is false and other part is trueThe first part of the statement is true and other part is false

19. Cantilever beams are always in equilibrium, whether you form the equilibrium equations or not.

Don't KnowFalseMaybeTrue

20. The couple and the other two force systems in free body diagrams can be easily simplified.

Statement is wrongStatement is right if we remove ‘force’ partStatement is rightStatement is right if we remove ‘couple’ part

21. The generation of equal equations available for equilibrium as the unknown loadings always guarantees the stability of the body.

TrueFalseDon't KnowMaybe

22. Just like the collinear forces for free body diagrams there are collinear couple and the net moment is taken out from it.

The first part of the statement is true and other part is falseThe first part of the statement is false and other part is false tooThe first part of the statement is true and other part is true tooThe first part of the statement is false and other part is true

23. For equilibrium, the net force acting on the body is zero.

MaybeFalseDon't KnowTrue

24. A force is developed by a support that not allows the ________ of its attached member.

SubtractionTranslationAdditionRotation

25. The supports in the 3D are having more than three reaction forces. Because they are having three axis on which the components of the forces need to be zero.

The first part of the statement is false and other part is trueThe first part of the statement is false and other part is false tooThe first part of the statement is true and other part is falseThe first part of the statement is true and other part is true too