Centroids and Moments of Inertia: Master the Fundamentals

Question 1

Calculate the moment of inertia per unit length about the axis of symmetry parallel to one side of a square cross-section with a side length of 10 cm and a thickness of 2 cm.

Accepted Answer

666.67 cm^4

Answer

333.33 cm^4

Answer

2000 cm^4

Answer

1333.33 cm^4

Question 2

The moment of inertia about its centroidal axis for a rectangular area with width 'b' and height 'h' is expressed as:

Accepted Answer

(bh^3)/12

Answer

(hb^3)/6

Answer

(bh^3)/6

Answer

(hb^3)/12

Question 3

For a solid hemisphere with radius 'R', its centroid is situated at a distance of what fraction of 'R' from the base?

Accepted Answer

3/8

Answer

1/2

Answer

1/4

Answer

1

Question 4

The centroid of a triangle with base 'b' and height 'h' is located at a distance of what fraction of 'h' from the base?

Accepted Answer

1/3

Answer

1/4

Answer

1/6

Answer

1/2

Question 5

Calculate the centroid of a triangle with vertices (0,0), (4,0), and (0,3).

Accepted Answer

(2/3,1)

Answer

(0,1)

Answer

(1,2/3)

Answer

(1,1)

Question 6

Determine the centroid of a semicircular area with radius 'r'.

Accepted Answer

(4r/3π, r/2)

Answer

(4r/3π, r)

Answer

(r/2, r/2)

Answer

(r, r/2)

Question 7

Calculate the distance of the centroid from the diameter of a semicircular area with radius 'r'.

Accepted Answer

r/2

Answer

r/4

Answer

r/6

Answer

r/8

Question 8

Explain how to determine the centroid of a composite area.

Accepted Answer

Weighted average of the centroids of its constituent areas

Answer

Sum of the centroids of its constituent areas

Answer

Product of the centroids of its constituent areas

Answer

Quotient of the centroids of its constituent areas

Question 9

Determine the location of the centroid of a triangle.

Accepted Answer

The intersection point of the three medians

Answer

The intersection point of the three altitudes

Answer

The intersection point of the three bisectors

Answer

The intersection point of the three perpendicular bisectors

Question 10

Determine the radius of gyration of a circular section about its centroidal axis.

Accepted Answer

R

Answer

R/2

Answer

R/4

Answer

R/8

Question 11

Which of the following is NOT an essential component of the second moment of area?

Accepted Answer

Mass

Answer

Area

Answer

Centroid

Answer

Moment of inertia

Question 12

The centroid of a rectangular area with sides of length 'a' and 'b' is located at:

Accepted Answer

The geometrical center

Answer

The midpoint of one side

Answer

The intersection of the diagonals

Answer

The corner of the rectangle

Question 13

The moment of inertia of a circular area with radius 'r' about its centroidal axis is:

Accepted Answer

πr^4/4

Answer

πr^2/2

Answer

πr^4/8

Answer

πr^2/4

Question 14

According to the parallel axis theorem, the moment of inertia of an area about an axis parallel to the centroidal axis and at a distance 'd' from it is:

Accepted Answer

The sum of the moment of inertia about the centroidal axis and the product of the area and the square of the distance between the axes

Answer

Equal to the moment of inertia about the centroidal axis

Answer

The difference between the moment of inertia about the centroidal axis and the product of the area and the square of the distance between the axes

Answer

Equal to zero

Question 15

Which of the following shapes has the highest moment of inertia for a given area?

Accepted Answer

Circle

Answer

Square

Answer

Rectangle

Answer

Triangle

Question 16

The area moment of inertia of a cross-section is used to calculate the:

Accepted Answer

Bending stress

Answer

Shear stress

Answer

Torsional stress

Answer

Axial stress

Question 17

For a rectangular area, the moment of inertia about its centroidal axis that is parallel to one side is expressed as:

Accepted Answer

I = (bh^3)/12

Answer

I = (bh^3)/3

Answer

I = (bh^2)/6

Answer

I = bh^2

Question 18

Which shape has the highest polar moment of inertia?

Accepted Answer

Circle

Answer

Square

Answer

Rectangle

Answer

Triangle

Question 19

Where is the centroid of an equilateral triangle located?

Accepted Answer

One-third of the height from the base

Answer

One-half of the height from the base

Answer

Two-thirds of the height from the base

Answer

One-fourth of the height from the base

Question 20

Which factor does NOT influence the moment of inertia of a beam?

Accepted Answer

Applied forces

Answer

Elastic modulus

Answer

Cross-sectional shape

Answer

Length

Question 21

Among the given shapes, which one has the smallest polar moment of inertia?

Accepted Answer

Hollow circle

Answer

Solid circle

Answer

Solid square

Answer

Hollow square

Question 22

Which theorem is used to determine the moment of inertia of a composite shape?

Accepted Answer

Parallel axis theorem

Answer

Perpendicular axis theorem

Answer

Polar moment of inertia theorem

Answer

Transfer theorem

Question 23

Which of the following is NOT a type of moment of inertia?

Accepted Answer

Force moment of inertia

Answer

Mass moment of inertia

Answer

Polar moment of inertia

Answer

Area moment of inertia

Question 24

Select the formula used to calculate the moment of inertia (Ixx) about the x-axis for a rectangular area with width 'b' and height 'h':

Accepted Answer

(bh^3)/12

Answer

(bh^3)/3

Answer

bh^3

Answer

b^2h^2

Question 25

Which shape possesses the highest moment of inertia for a given cross-sectional area?

Accepted Answer

Solid circle

Answer

Solid square

Answer

Solid triangle

Answer

Hollow circle

Question 26

Indicate the units of moment of inertia:

Accepted Answer

kg-m^2

Answer

m^4

Answer

m^3

Answer

kg-m

Question 27

Identify the shape that does not have its centroid coinciding with its geometric center:

Accepted Answer

Triangle

Answer

Circle

Answer

Square

Answer

Rectangle

Question 28

Which of the following shapes has its centroid at the geometric center?

Accepted Answer

Circle

Answer

Rectangle

Answer

Triangle

Answer

Semi-circle

Question 29

What are the coordinates of the centroid of a triangle with vertices at (0,0), (a,0), and (0,h)?

Accepted Answer

(a/3, h/3)

Answer

(a/2, h/2)

Answer

(2a/3, 2h/3)

Answer

(a/4, h/4)

Question 30

What is the moment of inertia of a solid cylinder about its own axis?

Accepted Answer

(1/2)mr²

Answer

(1/4)mr²

Answer

mr²

Answer

2mr²

Question 31

Which of the following is NOT a valid type of moment of inertia?

Accepted Answer

Force moment of inertia

Answer

Mass moment of inertia

Answer

Area moment of inertia

Answer

Volume moment of inertia

Question 32

Calculate the moment of inertia about the x-axis for a rectangular area with width 'b' and height 'h'.

Accepted Answer

(1/12)*b*h^3

Answer

(1/3)*b*h^3

Answer

(1/6)*b*h^3

Answer

(1/24)*b*h^3

Question 33

Calculate the moment of inertia about the centroidal x-axis for a semicircular area with radius 'r'.

Accepted Answer

(1/8)*π*r^4

Answer

(1/12)*π*r^4

Answer

(1/4)*π*r^4

Answer

(1/16)*π*r^4

Question 34

Determine the mass moment of inertia of a non-uniform rod with variable density 'ρ' along its length 'L'.

Accepted Answer

I = ∫ρ(x) * x² * dx

Answer

I = ∫ρ(x) * x³ * dx

Answer

I = ∫ρ(x) * x * dx

Answer

I = ∫ρ(x) * x / dx

Question 35

Find the centroid of a thin rectangular plate with length 'a' and width 'b'.

Accepted Answer

(a/2, b/2)

Answer

(3a/4, 3b/4)

Answer

(a/3, b/3)

Answer

(a/4, b/4)

Question 36

A rectangular plate has a width of 4 meters and a height of 6 meters. What are the coordinates of its centroid?

Accepted Answer

(2, 3)

Answer

(1, 1.5)

Answer

(4, 6)

Answer

(0, 0)

Question 37

Which statement accurately defines the moment of inertia?

Accepted Answer

Moment of inertia represents an object's resistance to changes in its rotational motion.

Answer

Moment of inertia is a measure of an object's weight.

Answer

Moment of inertia measures an object's linear velocity.

Answer

Moment of inertia is a measure of an object's density.

Question 38

A circular plate has a radius of 10 centimeters. What is its moment of inertia about an axis perpendicular to the plate and passing through its center?

Accepted Answer

π * 10^4 cm^4

Answer

π * 10^3 cm^4

Answer

π * 10^6 cm^4

Answer

π * 10^2 cm^4

Question 39

The moment of inertia of a beam's cross-section is directly proportional to its:

Accepted Answer

Resistance to bending

Answer

Material strength

Answer

Length

Answer

Weight

Question 40

To determine the centroid of a composite shape made of a rectangle and a semicircle, you should:

Accepted Answer

Calculate the centroid of each individual shape and then apply the composite centroid formula.

Answer

Use the centroid formula for a single rectangular shape.

Answer

Estimate the centroid visually.

Answer

Simply average the centroids of the rectangle and semicircle.

Question 41

The parallel axis theorem is used to calculate the moment of inertia of a body about an axis that is:

Accepted Answer

Parallel to the body's centroidal axis, but shifted from it.

Answer

None of the above.

Answer

Passing through the body's center of mass.

Answer

Perpendicular to the body's centroidal axis.

Question 42

A thin, hollow cylindrical tube has a greater moment of inertia about its longitudinal axis compared to a solid cylinder with the same mass and radius because:

Accepted Answer

The mass of the hollow cylinder is distributed further away from the axis of rotation.

Answer

The hollow cylinder has a larger surface area.

Answer

The hollow cylinder is lighter.

Answer

The hollow cylinder is made of a different material.

Question 43

Increasing the moment of inertia of a beam's cross-section in a structural design problem would:

Accepted Answer

Increase the beam's resistance to bending.

Answer

Have no effect on the beam's resistance to bending.

Answer

Increase the beam's weight.

Answer

Decrease the beam's resistance to bending.

Question 44

A thin, rectangular plate has a larger moment of inertia about an axis passing through its center and perpendicular to its plane compared to an axis passing through its edge and parallel to the plate. This is because:

Accepted Answer

The mass is distributed further from the axis of rotation when the axis passes through the center.

Answer

The plate is thinner in the first case.

Answer

The plate is made of a denser material in the first case.

Answer

The plate is longer in the first case.