- #1
inferno298
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Homework Statement
Question in full detail:
Postal workers on planet Gortak want to drill a straight
tube through the planet, starting at Post Office 1, passing
through the center of the planet, and ending on the other side
at Post Office 2. They plan to release small packages contain-
ing mail into the tube from P.O. 1 and have others grab them
at P.O. 2. Gortak has g = 9.6 m/s^2, and a radius of 6400 km.
When it is located within the shell of a planet, the weight of a
particle of mass m is m*g*r/R, where r is its distance from the
center of the planet. Assume that there is no air resistance.
Compute a) the position r of the package 1883 s after it has
been released, and cool.gif its speed at that time. Note: r is posi-
tive if the package is on the same side of planet as P.O. 1, and
negative if it is on the same side as P.O. 2.
Attempts:
I don't want anyone to really solve it, but what I want is just help setting up the differential equation or at least a push in the right direction.
I believe its going to be a second order diff'Eq, and related to using F=ma.
so ma=mg since there is no air resistance.
m dV/dt-mg=0, no external forces other than gravity so it should be a homogenous equation. I get stuck here because I feel I am missing something in the equation, and not sure how to take into account the object going back and forth.
Oh wait maybe its a Simple harmonic oscillator problem?
Any help would be nice, its due in about 6 days. Again no solutions to the Diff'eQ please. I want help in setting up the equation or helpful advice in the right direction. My professor said to use Mathematica for part of it so I don't know if that means the solutions are only going to be obtained numerically or graphically.
Thanks!