Assume that the earth is a solid sphere of uniform density and a tunnel is dug along its diameter throughout the earth. It is found that when a…

Assume that the earth is a solid sphere of uniform density and a tunnel is dug along its diameter throughout the earth. It is found that when a particle is released in this tunnel, it executes a simple harmonic motion. The mass of the particle is $\displaystyle 100$ g . The time period of the motion of the particle will be (approximately) (Take $\displaystyle \mathrm{g}=10 \mathrm{~m} \mathrm{~s}^{-2}$, radius of earth $\displaystyle =6400 \mathrm{~km}$ )