Question

A thin spherical shell of mass M and radius R has a small hole. A particle of mass m is released at the mouth of the shell . Then

• A. The particle will execute S.H.M inside the shell
• B. The particle will oscillate inside the shell, but the oscillations are not simple harmonic
• C. The particle will not oscillate, but the speed of the particle will go on increasing
• D. None of these

Answer 1

The correct option is D None of these

It was Newton who mathematically proved that the mass of the earth should be treated with its mass concentrated at it center. When an object is placed outside a thin shell then the vector sum of all gravitational forces contribute to the resultant. But when the object lies inside the shell these forces cancel out exactly.
When a particle of mass $m$ is released at the mouth of the shell the particle will not be influenced by gravitational field and will come out as such.(net gravitational field $=$0)