Four spheres, each of diameter `2a and mass M` are placed with their centres on the four corners of a square of side `b`. Calculate one side of the square taken as the axis.

Explanation

To calculate the moment of inertia of the system of four spheres placed at the corners of a square with respect to one side of the square, we can follow these steps:

### Step 1: Understand the Configuration
We have four solid spheres, each with a diameter of \(2a\) and mass \(M\), placed at the corners of a square with side length \(b\). We need to find the moment of inertia about one side of the square.

### Step 2: Moment of Inertia of a Solid Sphere
The moment of inertia \(I\) of a solid sphere about its own diameter is given by the formula:
\[
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