if you drilled a hole through the earth and dropped an object would it come out the other end?

Answer 1

This is a great question, and it is one that I discuss with my Physics classes every year. While everyone recognizes the impossibility of tunneling through the Earth due to the immense pressures and temperatures, the presence of circulating fluids, etc., it is possible to think about the problem on a theoretical level. Let's simplify the problem by assuming that the Earth is stationary and perfectly spherical (in reality it is an oblate spheroid).
We begin by neglecting air friction in the tunnel. Let's say you dropped an object through the tunnel right at the Earth's surface. As the object falls, it picks up speed, reaching 10 m/s (32 ft/s) after 1 second, 20 m/s (64 ft/s) after 2 seconds, and so on. At the center, its speed is a whopping 9,900 m/s (22,000 miles per hour). It will have taken 19 minutes to fall to the center.
Because the core is much denser than the surrounding mantle, the gravitational acceleration increases slightly until you reach the core-mantle boundary, where gravity is 10.7 m/s^2. From this point on, gravity decreases until it is zero at the center. As the object travels past the center, gravity starts increasing, which starts to slow the object down. This doesn't happen immediately, however, because it is traveling quite fast. In fact, the object will continue to slow down until it has just reached the surface on the other side of the Earth. The entire journey will have taken 38 minutes. At this point, the object falls back through the hole, returning to its original position. This type of motion is called simple harmonic motion, much like a mass bouncing up and down on a spring, or a pendulum moving back and forth.
Now let's consider the case where you throw the object down the hole instead of dropping it from rest. Now the object will rise up in the air a short distance on the other side of the Earth before reversing direction and plummeting through the hole again. With no air friction, the object will oscillate back and forth indefinitely.
What happens if there is air friction? You have two problems here. First, the weight of the air column in the hole causes the air to become quite dense as you descend. At a depth of only 10 km (6 miles), air has a density close to that of water. Air friction becomes so great that the object slows down tremendously. The trip suddenly takes days or years rather than minutes. Second, the object will never make it back to the surface, and eventually it will come to rest at the center.

Answer 2

Yup... presuming it was thrown with sufficient initial velocity to overcome all of the air resistance it will encounter.
Newton did a cool thing with shells of the Earth: he imagined a near infinite number of globes, each as thin a shell as can you imagine, all centered on the Earth with an ever-diminishing diameter for each shell. The set of global shells would represent the entire make-up of the Earth. The ball would be traveling down through each of these shells in sequence.
Newton demonstrated that the force of gravity as the ball travels within the outer shell of the set is identical to that of the inside-most shell. He showed that gravity for a sphere is uniform wherever you are within it.
The ball would be positively accelerated with gravity on its way into the center, then slowed equally as it departed the center. So, without air in the cylinder through the Earth, the ball would reach the other side. Notice we said nothing about the spinning Earth and the effect of this on the falling object.

BUT YOU set the criteria, which said nothing about vacuums or near-infinitely dense and small objects, so there IS air in the cylinder through the Earth, and you DID drop the ball - not throw it, so, NO - don't expect to ever see the ball again. You just don't know how many times I have dropped an object down such a cylinder, and they are never seen again.

There is a great science fiction short story about this - where an Earthman in space is captured spying on Mars as a set of interstellar aliens are working there. They throw him down such a well... Anybody know the name of the story? The understanding of the manner in which he escapes is a great physics lesson.

Answer 3

no,
if you could somehow get this tunnel to remain open (this would be extremely difficult for many reasons - the first of which is that the earth is not solid), the rock would end up somewhere in the center.

The force of gravity is what causes an object to fall. The earth is a very large object, so it has a very large gravitational force (9.8 m/s/s is the rate at which abjects accelerate towards the earth).

If an object were dropped into this hole, it would experience less and less acceleration in the direction towards the center of the earth (down) until it reached the center. At the center, the object would be pulled equally in all directions by the attraction to the earth. With equal force in all directions, the object would merely float in the center of the hole through the earth.

Answer 4

not quite, you could treat it as an oscillation issue, assuming that you did it on the axis so that the variable rotation speed was not an issue you still face friction with air, if you fell in vacuum through a perfect sphere you might make it out the far side without stopping. Otherwise there will always be a friction factor that will cause you to fall short and fall back until you ended at rest in the center.

Answer 5

No. You would not be able to drill thought the earth. It is to hot and any object would melt

Answer 6

This is a cope out answer it would depend on how much trust you added while dropping. Guessing at some point it would have to overcome gravity pull. That was a guess thanks for interesting questions that cause thought. Wondinging if where you place hole would make a difference.

Answer 7

Nope, The earths core would burn it up into nothing :p

Answer 8

no