# Gravity Question

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#### aetherius

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I'm curous about gravity at the exact center of a massive body like a planet.<br /><br />Here's a hypothetical--You drill a tunnel to within one inch of the center of an earth sized planet. (Assume a planet of "dirt") <br /><br />Question 1: Do you still experience the same (approximate) pull toward the center of the planet that you did on the surface?<br /><br />Question 2,3: Given you are 1 inch from the center; What would you experience if you used a shovel to dig beyond the center? Would you notice any difference in the way the dirt falls off your shovel?

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#### vogon13

##### Guest
You will be weightless at the center. In fact, you become lighter all the way down. Mass above you has gravity to cancel out gravity from mass below. All balanced out at center.<br /><br />You did not ask, but if you had a large pipe laying on the surface of earth, pumped a vacuum in it, and traveled thru the pipe (on a rocket sled or something) at 17,500 mph, you would be weightless on the surface too. In this case the centripetal force negates gravity.<br /><br />All kinds of neat physics experiments remain undemonstrated. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

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#### larper

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Hmmm. No, your pipe analogy has some flaws.<br /><br />Traveling in orbit (whether at the earth's surface in your pipe, or in LEO), means you are in free fall. You are experiencing the acceleration due to gravity, but you are traveling parallel to the surface fast enough to miss it as you fall toward it.<br /><br />The centripetal force does not negate gravity. Gravity IS the centripetal force. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

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