# What is the moment of inertia about an axis through A?Three particles are placed at the vertices of a triangle ABC. The particles weigh .3 kg, 0.1 kg and 0.2 kg respectively. The length of the...

What is the moment of inertia about an axis through A?

Three particles are placed at the vertices of a triangle ABC. The particles weigh .3 kg, 0.1 kg and 0.2 kg respectively. The length of the sides AB, BC and CA are 0.5m, 0.3m and 0.4m resp.

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### 1 Answer

The moment of inertia is the sum of the products of the mass of the bodies with the square of the distant from the axis. When the moment of inertia is being found about an axis through A, we need the following values:

Distance between A and B is 0.5 m and the mass of body at B is 0.1 kg

Distance between A and C is 0.4 m and the mass of body at C is 0.2 kg

To calculate the required moment of inertia, we need to add 0.1*0.5^2 and 0.2*0.4^2. This is equal to .025 + .032 = .057 kg*m^2.

**The required moment of inertia is .057 kg*m^2**