This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Mass Moment of Inertia”.

1. What is the product of the mass and the square of the distance of the center of gravity of the mass from an axis?

a) Moment of inertia

b) Mass moment of inertia

c) Center of gravity

d) Product of inertia

View Answer

Explanation: The product of the mass and the square of the distance of the center of gravity of the mass from an axis is known as the mass moment of inertia about that axis.

2. What is the unit of mass moment of inertia?

a) m^{4}

b) m^{6}

c) N

d) m^{2}

View Answer

Explanation: The mass moment of inertia is the product of moment of inertia and area . so L

^{4}x L

^{2}= L

^{6}. so its unit will be m

^{6}.

3. What is mass moment of inertia of circular plate?

a) Md^{2}/3

b) Md^{2}/12

c) Mr^{2}/4

d) Mr^{2}/3

View Answer

Explanation: The mass moment of inertia of circular plate is Mr

^{2}/4.

4. What is the mass MOI of a rectangular plate about x-axis passing through the C.G of the plate if the y-axis is parallel to d and perpendicular to b?

a) Mb^{2}/12

b) Md^{2}/12

c) Md^{2}/6

d) Mb^{2}/6

View Answer

Explanation: As the mass MOI is to be find along the x-axis, it would be Md

^{2}/12.

5. What is the mass MOI of right circular cone of radius R and height H about its axis?

a) 4MR^{2}/10

b) MR^{2}/10

c) 3MR^{2}/10

d) MR^{2}/12

View Answer

Explanation: The mass MOI of right circular cone of radius R and height H about its axis is 3MR

^{2}/10.

6. What is the mass MOI of a hollow circular cylinder if R is the outer diameter and r is the inner diameter?

a) M(R + r)/4

b) M(R – r )/4

c) M(R+ r)/2

d) M(R – r)/2

View Answer

Explanation: The mass MOI of a hollow circular cylinder is M(R + r)/4 where R is the outer diameter and r is the inner diameter.

7. What is the mass MOI of a rectangular plate about y-axis passing through the C.G of the plate if the y-axis is parallel to d and perpendicular to b?

a) Mb^{2}/12

b) Md^{2}/12

c) Md^{2}/6

d) Mb^{2}/6

View Answer

Explanation: As the mass MOI is to be find along the y-axis, it would be Mb

^{2}/12.

8. The product of inertia at the principal axes is

a) Minimum

b) Unit

c) Zero

d) Maximum

View Answer

Explanation: The moment of inertia about x-axis and about y-axis , on the axis they are zero. So the product of inertia will be zero in the principal axis.

9. What is the unit of product of inertia ?

a) mm^{4}

b) mm^{2}

c) mm

d) mm^{3}

View Answer

Explanation: The unit of product of inertia is same as that of moment of inertia I.e. mm

^{4}.

10. What is the product of inertia of the given following section?

a) 50mm^{4}

b) 625mm^{4}

c) 125mm^{4}

d) 250mm^{4}

View Answer

Explanation: The product of inertia = area x points of C.G

= ( 10×5) x 5 x 2.5 = 625mm

^{4}.

11. What is the product of inertia of a circle of diameter 10mm?

a) 1862mm^{4}

b) 1945mm^{4}

c) 1963mm^{4}

d) 2014mm^{4}

View Answer

Explanation: The product of inertia = area x C.G

= πx 10×10 / 4 x 5×5 = 1963mm

^{2}.

**Sanfoundry Global Education & Learning Series – Strength of Materials. **

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