Two concentric spherical shells have masses M1, M2 and radii R1, R2 (R1<R2). What is the force exerted by this system on a particle of mass m1 if it is placed at a distance (R1 + R2)/2 from the center?

Given, the masses of two shells, M1, M2 and radii R1, R2.

Now, the distance of the particle is


is present outside the first shell while inside the second shell. So, there’s no field due to the larger sphere, and only the smaller one exerts force.


Therefore, the force is given by





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