Suppose that a hole has been drilled through the center of the earth, and that an object is droppped into this hole. Write a first order linear differential equaiton for the object's velocity, v as a function of the distance r from the earth's center (i.e, and equation involving dv/dr), and solve it to determine the speed the object achieves as it reaches the center of the earth. Check this speed with the result you get from simple conservation of energy considerations. Consider the Earth's mass density to be uniform throughout.
Hint : recall Gauss' law as it applies to the gravitational field of a spherically symmetric mass distribution
The Attempt at a Solution
I am having trouble relating Gauss' law to this problem , and from there, I don't know how to use the equation hopefully involving velocity and radius to use it in my differential equation. I'm very lost on how to start this problem. I don't need help doing the math, just the concept is not clicking.
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