This set of Engineering Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Moments of Inertia of Areas”.

1. Unit for moment of inertia is _____________

a) m^{3}

b) m^{4}

c) m^{2}/sec

d) m^{3}/sec

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. Since here we are considering the planar objects the area will have unit of m2 and square of distance gives another m

^{2}product is m

^{4}.

2. Moment of inertia of circle about the axis which is passing through its center and perpendicular to that circle is _____________

a) πd^{4}/32

b) πd^{3}/32

c) πd^{3}/16

d) πd^{4}/16

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. And this gives the moment of inertia of any planar section.

3. Moment of inertia of a rectangle whose base is b and height is h and axis is along base is __________

a) b*h^{3}/3

b) h*b^{3}/3

c) b*h^{4}/6

d) b*h^{3}/12

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. And this gives the moment of inertia of any planar section.

4. Moment of inertia of a rectangle whose base is b and height is h and axis is alongside of height is ________

a) b*h^{3}/3

b) h*b^{3}/3

c) b*h^{4}/6

d) b*h^{3}/12

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. And this gives the moment of inertia of any planar section.

5. Moment of inertia of a triangle having base as b and height as h and axis is along the centroid and parallel the base.

a) b*h^{3}/12

b) b*h^{3}/24

c) b*h^{3}/36

d) b*h^{3}/6

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. And this gives the moment of inertia of any planar section.

6. Moment of inertia of a triangle having base as b and height as h and axis is along the centroid and parallel the height.

a) b*h^{3}/12

b) h*b^{3}/36

c) b*h^{3}/36

d) b*h^{3}/6

View Answer

Explanation: The moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity. And this gives the moment of inertia of any planar section.

7. A rectangle is having base b and height h. The ratio of the moment of inertia when axis is passing through its base to moment of inertia of when axis passing through center of gravity and parallel to base is ___________

a) 3

b) 4

c) 12

d) 9

View Answer

Explanation: Moment of inertia of triangle having base b and height h when axis passing through the center of gravity is bh3/12 and moment of inertia when axis passing through base is bh3/3 and ratio is asked it gives 4.

8. A triangle is having base b and height h. The ratio of the moment of inertia when axis is passing through its base to moment of inertia of when axis passing through centroid and parallel to base is ______

a) 3

b) 6

c) 12

d) 9

View Answer

Explanation: Moment of inertia of triangle having base b and height h when axis passing through the centroid is bh3/36 and moment of inertia when axis passing through base is bh3/12 and ratio is asked it gives 3.

9. The moment of inertia is minimum when the axis is _________

a) passing through center of object

b) passing along x-axis

c) passing along y-axis

d) passing through centroid of object

View Answer

Explanation: The moment of inertia is minimum when the axis is passing through the centroid because the moment of inertia is sum of products of areas and squares of perpendicular distances from center of gravity.

10. In the polar moment of inertia the axis is perpendicular to _____________

a) depends on the object

b) x-axis

c) z-axis

d) y-axis

View Answer

Explanation: Polar moment of inertia is the sum of the moment of inertias of objects when axes are in same plane which are perpendicular to each other let us say x, y axis and polar moment of inertia is about z axis.

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