# Engineering Mechanics Questions and Answers – Composite Bodies

This set of Engineering Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Composite Bodies”.

1. A ______________ body consists of a series of connected “simpler” shaped bodies.
a) Composite
b) Non-composite
c) Digital
d) Binary

Explanation: A composite body consists of a series of connected simpler shaped bodies. That is the body is having two material as it’s constitutes. The main thing is that the single material is having the properties of two different materials.

2. Composite materials are of no use for the chemical engineers.
a) False
b) True

Explanation: The composite materials are of much importance to the chemical engineer. This means that the composite materials are variedly used in the chemical industries. It can be used in the bridges made for the pipelines, etc.

3. The composite materials are lighter than their constituent material.
a) False
b) True

Explanation: Yes the composite materials are lighter than the constituent material. This means that the density of the former is lighter than the latter. Thus imparting many qualities to the materials. Thus the material can be used variedly.

4. Composite materials can be of __________ shapes.
a) Any
b) Circular only
c) Rectangular only
d) Oval only

Explanation: The composite materials can be of any shape. This means that the shape of the material can be varied. Thus any shape can be imparted to the composite materials and then be used in the industries variedly.

5. Two of the things of the composite materials are to be known so that their properties can be varied. Which of the following is one of them?
a) Weight of the centre of gravity
b) Weight of the centre of body
c) Location of the centre of gravity
d) Location of the centre of mass

Explanation: The centre of the gravity’s location and the weight of the composite body is needed to be known. This means that if both of the quantities of the composite body is known then the properties of the body can be altered. Thus both are very important things to be known about the composite bodies.
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6. The centre of mass for the composite body is the ratio of ________ to _________
a) The product of centroid and mass to the total weight
b) The addition of centroid and weight to the total weight
c) The subtraction of centroid and weight to the total weight
d) The product of centroid and mass to the total mass

Explanation: The product of the centroid of the section to its mass to the total mass of the body is the centre of mass. Thus the answer. The ratio is generally used to locate the coordinate of the centroid or the centre of mass.

7. The total of all the masses of small particles adds up to give the total body mass of the composite body. This mass lies along with gravity gives a force vector which is being passed by ________
a) Axis of rotation
b) Axis of rolling
c) Centre of Gravity
d) Centre of mass

Explanation: The total body mass along with the product of gravity always passes through the centre of gravity. All the forces are parallel is the right answer. Thus the total sum of all these small weights adds up to the total weight of the body. Which passes through the centre of gravity.

8. One of the uses of the centre of mass or centroid of the composite bodies is as in the simplification of the loading system the net force acts at the ___________ of the loading body.
a) Centroid
b) The centre axis
c) The corner
d) The base

Explanation: In the simplification of the loading system the net force acts at the centroid of the composite body. That is if the loading system is in the form of the triangle then at the distance 2 by 3 of the base the net force of the loading will act. And the load will be half the area of the loading.

9. If any external force also is applied on the distributed loading on the composite body then?
a) The net force will act at the centroid of the structure only
b) The net load will not be formed as all the forces will be cancelled
c) The net force will act on the base of the loading horizontally
d) The net force will not to be considered, there would be a net force of the distribution, and rest will be the external forces

Explanation: The external forces are treated differently. They are not added by the force of the distributed loading. That is the force not only acts at the centroid always. It can be shifted also. Depending on the external forces. Thus the use of centroid or centre of mass.

10. A composite body is consisted of __________ number of particles.
a) Infinite
b) Finite
c) Hundreds
d) Thousands

Explanation: The various bodies are composed of infinite number of particles. They are very small in size. They can’t be seen by our naked eyes. Thus the number of particles is not thousands nor hundreds. But it is uncountable.

11. We use sometimes the measures to know the direction of moment. It is done by right handed coordinate system. Which is right about it for the composite bodies (consider the mentioned axis to be positive)?
a) Thumb is z-axis, fingers curled from x-axis to y-axis
b) Thumb is x-axis, fingers curled from z-axis to y-axis
c) Thumb is y-axis, fingers curled from x-axis to z-axis
d) Thumb is z-axis, fingers curled from y-axis to x-axis

Explanation: As right handed coordinate system means that you are curling your fingers from positive x-axis towards y-axis and the thumb which is projected is pointed to the positive z-axis. Thus visualizing the same and knowing the basic members of axis will not create much problem.

12. What is not the condition for the equilibrium in three dimensional system of axis for the composite bodies?
a) ∑Fx=0
b) ∑Fy=0
c) ∑Fz=0
d) ∑F≠0

Explanation: For the equilibrium in the three dimensional system of 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.

13. Determine the x coordinate of centroid of the shape shown.

a) 0.410m
b) 1.410m
c) 2.410m
d) 0.10m

Explanation: The weight of the body is the sum of the all the small weights that are been applied by all the particles. The smaller the particle the smaller the weight it applies. Thus the total weight of the body is the summation of all the infinite number of small weights applied to the body.

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