Suppose a tunnel is dug along the diameter of the earth. A particle is from a point distance h directly above the tunnel. The earth's density is assumed uniform and the friction is neglected. Then:

(1) The acceleration on the particle will be maximum just at the point of release.
(2) The particle will drop to the centre of the earth.
(3) The particle will have harmonic oscillation.
(4) The particle will have maximum speed when passing through the centre of the earth.