# Static force analysis - Theory of Machines - 1

Q.  Which of the following statements is/are true?

1. Static force analysis does not consider inertia forces along with static forces
2. The SI unit of mass moment of inertia is kg/m2
3. Mass moment of inertia of a thin disc about its diameter is given by (mr2) / 2

- Published on 06 Aug 15

a. Only 1
b. Only 2
c. Only 3
d. All the above statements are true

#### Discussion

• Sravanthi   -Posted on 19 Oct 15
Mass moment of inertia

- Mass moment of inertia of any rigid body measures resistance to angular acceleration.

- Mass moment of inertia is defined as the distance from a reference line where whole mass of the body is concentrated.

- It is expressed as I = mk2, therefore SI unit of mass moment of inertia is kg-m2

- Mass moment of inertia of a thin disc about its diameter is given as mr2 / 4

- Mass moment of inertia of a thin disc about an axis through C.G and perpendicular to the disc plane is given as,

I = mr2 / 2

Static force analysis

In static force analysis, inertia forces are negligible when compared with static forces. Hence the analysis of mechanism is known as static force analysis.

Dynamic force analysis

In dynamic force analysis, inertia forces along with static forces are considered.

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