The density inside a solid sphere of radius a is given by `rho=rho_0/r`, where `rho_0` is the density ast the surface and r denotes the distance from the centre. Find the graittional field due to this sphere at a distance 2a from its centre.

Explanation

To find the gravitational field due to a solid sphere of radius \( a \) with a density given by \( \rho = \frac{\rho_0}{r} \) at a distance \( 2a \) from its center, we can follow these steps:

### Step 1: Determine the mass of the sphere
The density of the sphere varies with the distance \( r \) from the center. We can express the mass of a thin spherical shell of radius \( r \) and thickness \( dr \) as:

\[ dm = \rho \cdot dV \]
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