### Author Topic: Solution of Question 4  (Read 2300 times)

#### Chaojie Li

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##### Solution of Question 4
« on: March 19, 2015, 09:13:07 PM »
Using Newton shell theorem (see [Section 6 of Lecture 25]) prove that if Earth was a homogeneous solid ball then the gravity pull inside of it would be proportional to the distance to the center.
« Last Edit: March 20, 2015, 08:13:53 AM by Victor Ivrii »

#### Chaojie Li

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##### Re: Solution of Question 4
« Reply #1 on: March 19, 2015, 09:14:32 PM »
Yes exactly: if you drill a tunnel and drop a ball it will be a harmonic oscillations $r'' = - kr$ with $k= g/R$.