In the previous problem, if tunnel is dug along a chord, find time period.

Explanation

Restoring force
`F^'=Fsintheta=-(GM_em)/(R_e^3)x*y/x=-(GM_em)/(R_e^3)y`
`a=(F^')/(m)=-(GM_e)/(R_e^3)y=-omega^2y`
`T=2pisqrt((R_e^3)/(GM_e))`
Time period remains same.