- #1
Pushoam
- 962
- 51
Homework Statement
Homework Equations
The Attempt at a Solution
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The thing to remember is that inside the Earth surface, the gravitational field does not remain inversely proportional to ##r^2##.
The equation of motion is
## \ddot r = \frac { -gr} R## ....(1)
This means that the particle will oscillate between the two points on the surface with angular frquency ## \omega = \sqrt{ \frac { g} R}##. ...(2)
## T= \frac { 2\pi } {\omega }##...(3)
The required time is ## \frac { T} 2 = 42.3 ~ min##...(4)
Hence, the correct option is (c).
The time taken for going from one point to another point of the Earth surface is independent of the distance between the two points.
Then, when I go into an underground room, I need to move for going from one point to another. Is it because of friction force?
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