A spherical hole is made in a solid sphere of radius R. The mass of the sphere before hollowing was M. The gravitational field at the centre of the hole due to the remaining mas is
By the principle of superposition of fields
→E=→E1+→E2=
Here →E = net field at the centre of hole due to entire mass
→E1 = field due to remaining mass
and →E2 = field due to mass in hole = 0
∴E1=E=(GMR3).r where r=R2∴E=GM2R2