# Engineering Mechanics Questions and Answers – Conditions for a Rigid-Body Equilibrium – 2

This set of Engineering Mechanics Quiz focuses on “Conditions for a Rigid-Body Equilibrium – 2”.

1. Free body diagrams don’t play any role in making the calculations on the conditions of the equilibrium of the body.
a) True
b) False

Explanation: The free body diagrams does play an important role in the formation of the conditions of the equilibrium of the rigid body. As the net forces are zero, the fbd helps us to take the measure of the same. That is to see whether the summation is really zero or not.

2. The net forces of acting on the body need to be zero. This is also applicable for the simply supported beams. This means that the support reaction is also counted in making the net force zero.
a) True
b) False

Explanation: The support reactions of the beam is also counted in the making of the forces zero. As far as the net force is concerned the support reaction does affect the conditions for the equilibrium of the body. Hence one needs to take care of the support reactions of the beam too.

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

a) 268N
b) 68N
c) 28N
d) 288N

Explanation: The summation of the forces needs to be zero. So does the summation of the moments need to zero. But talking about the angles, they not needed to zero. But the forces which are acting at particular angles, must needed to be equal to zero. The basic need of the forces to make the body in equilibrium.

4. If the body is in equilibrium, but it having a rotational curled ray shown in the free body diagram then:
a) The diagram is wrong
b) Such rotations can’t be shown in the fbds(free body diagrams)
c) The ray shown may be correct, but the body is not said to be in equilibrium
d) The body is said to be in equilibrium only, as the other forces will cancel out that rotation

Explanation: The body having equilibrium will not rotate at any cost. Yes, the diagram may contain the rotational array showing the couple being acted over the structure. But the thing is that the forces, i.e. the other forces which are outside the dependency of this rotation will cancel out this rotation and thus the body is in equilibrium.

5. If five forces are acting on the single particle and having an angle of 72˚ between each and are collinear, then:
a) The net force acting on the body is zero
b) The net force acting on the body is horizontal
c) The net force acting on the body is vertical
d) The net force acting on the body is at an angle of 45

Explanation: The net force acting on the body is zero. This means that the forces cancel out. This means that the body is in equilibrium and doesn’t need any of the external force to make itself in the equilibrium.
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6. Which of the following is correct?
a) There is only one type of support for the beams
b) There are only two types of support for the beams
c) There are only three types of support for the beams
d) There are various types of support for the beams and they are countless

Explanation: The support is the thing which a human decides. That can be anything. That is the support can be given in any way. The type of support also is important as different types of supports have different conditions for the equilibrium.

7. What does Newton’s second law states?
a) The rate of change of momentum is equal to the force applied
b) For every reaction, there is an opposite reaction
c) The body is tend to be rotated if the force is applied tangentially
d) The body is rest until a force is applied

Explanation: The requirement of the second law is important in the equilibrium of the body. Specially the rigid bodies. The rigid body particles are if are in motion then this law helps in making the conditions for the equilibrium of the body. As when the body will leave its state of motion and come in rest, etc.

8. Determine the vertical components of the reaction on the beam caused by the pin at Q.

a) 286N
b) 68N
c) 28N
d) 288N

Explanation: The summation of the forces needs to be zero. So does the summation of the moments need to zero. But talking about the angles, they not needed to zero. But the forces which are acting at particular angles, must needed to be equal to zero. The basic need of the forces to make the body in equilibrium.

9. Which of the following is correct?
a) The application of the conditions of the equilibrium of the body is valid only if the forces are collinear
b) The application of the conditions of the equilibrium of the body is valid only if the forces are parallel
c) The application of the conditions of the equilibrium of the body is valid only if the forces are perpendicular
d) The application of the conditions of the equilibrium of the body is valid throughout

Explanation: The application of the conditions of the equilibrium of the body is valid throughout. This means that the conditions are irrespective of the types of forces. The conditions are the basic rules that defines the equilibrium of the body and thus are applicable in any type of forces of the real axis.

10. Determine the horizontal components of the reaction on the beam caused by the pin at Q. The force 60N is multiplied by 10 and then is applied.

a) 0N
b) 445N
c) 45N
d) 40N

Explanation: The summation of the forces needs to be zero. So does the summation of the moments need to zero. But talking about the angles, they not needed to zero. But the forces are acting at particular angles.

11. 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 cancels out the rotation part of the body.
a) The first part of the statement is false and other part is true
b) The first part of the statement is false and other part is false too
c) The first part of the statement is true and other part is false
d) The first part of the statement is true and other part is true too

Explanation: The application of the support reaction forces does affect the conditions of the equilibrium of the body. Not only the external but the support reaction forces that are developed by the sake of external forces does develop a tending effect on the equilibrium of the body. Thus the support reaction forces also cancels the external forces.

12. Cantilever beams are always in equilibrium, whether you form the equilibrium equations or not.
a) True
b) False

Explanation: The thing is that the formation of the conditions only verifies that the body is in equilibrium or not. Thus if the cantilever is in equilibrium then also the condition needs to be applied. It will be wrong to justify the equilibrium only on the basis of structure.

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

a) 268N
b) 68N
c) 28N
d) 288N

Explanation: The summation of the forces needs to be zero. So does the summation of the moments need to zero. But talking about the angles, they not needed to zero. But the forces which are acting at particular angles, must needed to be equal to zero. The basic need of the forces to make the body in equilibrium.

14. Determine the vertical components of the reaction on the beam caused by the pin at Q. The force 60N is multiplied by 10 and then is applied.

a) 319N
b) 445N
c) 45N
d) 40N

Explanation: The summation of the forces needs to be zero. So does the summation of the moments need to zero. But talking about the angles, they not needed to zero. But the forces which are acting at particular angles, must needed to be equal to zero. The basic need of the forces to make the body in equilibrium.

15. 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.
a) The first part of the statement is false and other part is true
b) The first part of the statement is false and other part is false too
c) The first part of the statement is true and other part is false
d) The first part of the statement is true and other part is true too

Explanation: The application of the support reaction forces does affect the conditions of the equilibrium of the body. Not only the external but the support reaction forces that are developed by the sake of external forces does develop a tending effect on the equilibrium of the body. Thus the support reaction forces also cancels the external forces.

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