250+ TOP MCQs on Moment of Inertia of Section and Answers

This set of Strength of Materials Problems on “Moment of Inertia of Section”.

1. What is the moment of inertia of a circular section?
a) πD⁴/64
b) πD³/32
c) πD³/64
d) πD⁴/32
Answer: a
Clarification: The moment of inertia of a circular section is πD⁴/64.

2. What is the moment of inertia of a rectangular section about an horizontal axis through C.G?
a) bd³/6
b) bd²/12
c) b²d²/12
d) bd³/12
Answer: d
Clarification: The moment of inertia of a rectangular section about an horizontal axis through C.G is bd³/12.

3. What is the moment of inertia of a rectangular section about an horizontal axis passing through base?
a) bd³/12
b) bd³/6
c) bd³/3
d) bd²/3
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis passing through base is bd³/3.

4. What is the moment of inertia of a triangular section about the base?
a) bh²/12
b) bh³/12
c) bh³/6
d) bh²/6
Answer: b
Clarification: The moment of inertia of a triangular section about the base is bh³/12.

5. What is the moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base?
a) bh³/12
b) bh³/24
c) bh³/36
d) bh³/6
Answer: c
Clarification: The moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base is bh³/36.

6. What will be the moment of inertia of a circle in cm4 of diameter is 10cm?
a) a340
b) 410
c) 460
d) 490
Answer: d
Clarification: The moment of inertia of a circle is = πD⁴/64
= 491.07 cm⁴.

7. What will be the moment of inertia of the given rectangle about an horizontal axis passing through the base?

a) 1500 mm⁴
b) 1650 mm⁴
c) 1666 mm⁴
d) 1782 mm⁴
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis passing through base = bd³/3
= 5x10x10x10/3
= 1666.66 mm⁴.

8. What will be the moment of inertia of the given rectangular section about an horizontal axis through C.G.?

a) 350 mm⁴
b) 379mm⁴
c) 416mm⁴
d) 500mm⁴
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis through C.G = bd³/12
= 5x10x10x10/12
= 416.67 mm⁴.

9. What will be the moment of inertia of the given triangle about the base?

a) 20.33 mm⁴
b) 21.33 mm⁴
c) 24.33 mm⁴
d) 22.33 mm⁴
Answer: b
Clarification: The moment of inertia of a triangular section about the base = bh³/12.
= 4x4x4x4/12
= 21.33 mm⁴.

10. What will be the moment of inertia of the given triangle about an axis passing through C.G and parallel to base?

a) 6.1 mm⁴
b) 7.1 mm⁴
c) 8.1 mm⁴
d) 7.56 mm⁴
Answer: b
Clarification: The moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base = bh³/36.
= 4x4x4x4/36
= 7.11 mm⁴.

11. What will be the difference between MOI of two triangle sections is in 1st, MOI is taken about its base and in 2nd MOI is taken about its centroid?
a) bh³/12
b) bh³/18
c) bh³/36
d) bh³/24
Answer: b
Clarification: The moment of inertia of a triangular section about the base is bh³/12
The moment of inertia of a triangular section about an axis passing through C.G. is bh³/36
So the difference = bh³/12 – bh³/36 = bh³/18.

Strength of Materials Problems,