Center of the earth and gravity

Heres a thought that occured to me the other day.

Suppose you could drill a hole all the way through the earth and clear out the other end.

What would happen if you dropped a tennis ball into that hole, provided it could withstand the heat and pressure - in theory of course.

Would the ball reach the centre of the earth and stop due to gravity?

if you are disregarding heat and pressure, doesn't that encompass gravity?

That im unsure of, however isnt gravity linked to the mass of an object? The heat and pressure of motlen rock and metal within the earth produces the earths magnetic which protects us from harmful radiation.

Yes I have had this thought. I figure that it will fall all the way through and keep going till it is sling shot back and forth and finally stops in the center.

interesting

However that would mean being suspended in mid air! Could the tennis ball be held at the centre of the earth purely by the earths gravity?

Ideas people!

I belive that in the center of the earth, there is simply so much pressure that any object pressurized at the surface would be be immobilized after a short slingshot, as Ancient has described. If there was a slingshot effect, it would be very quick, and the object in itself would have to be at a great velocity to create the slingshot effect, If there is not much velocity, I believe an object would be immobilzed upon acquisition of the point of the center of the earth.

quote:

---

The heat and pressure of motlen rock and metal within the earth produces the earths magnetic

---

Do you think this is true? Normally the magnetic domains (form magnetic field) are adversely affected by heating as the molecules tend to become less aligned at higher temperatures?
this may indicate that ferro-magnetic material in the earth mantle is responcible for the earth's magnetic field?
Kind of off-topic but as the core is molten (liquid phase), an aspect is does the core tend to flow (tides) with the moon as does water on it's surface?
The tremendous pressure on the core would tend to make motion hard such as a solid therefore it could produce magnetic domains but on the other hand, that pressure would tend to have the same effect as it does in the oceans which do have currents?

cturtle, it sounds like you know so much but are unable to convey it in a coherant way. In all honesty, I have not understood maybe more than one of your posts. This is not meant to be a stab at you, but more a possible improvement in the way you transfer your thoughts to words.

As far as this tennis ball theory goes, if you dropped it in the hole, once it reaches the center it would most likely get sucked into one of the sides of the dense molten nickel (its nickel right?). Unless the core was perfectly circular (if thats even possible) and pulled the tennis ball in equal directions from all directions (assuming the tennis ball could withstand the enormous force, and prevent itself from being shredded) only then could the tennis ball float perfectly in the center. If the tennis ball had enough density and velocity, I agree that you would probably see a slingshot effect.

The immobalizing pressure theory is right if you are falling through the magma in the core. However, if you are dropping an object through a vacated hole, there will be no pressure. What causes gravity is the mass of the earth, so at the very center of the earth, you will have an equal amount of the earth's mass on every side of you, so the forces will cancel out, making you weightless at the center. Therefore, and object dropped through would be accelerated until it reached the center, at which point gravity would slow it down until it reached the other side of the planet, and started to fall back to the center.

quote:

---

However, if you are dropping an object through a vacated hole, there will be no pressure. What causes gravity is the mass of the earth, so at the very center of the earth, you will have an equal amount of the earth's mass on every side of you, so the forces will cancel out, making you weightless at the center.

---

Due note of gravity as an acceleration force acting on inertial mass! Acelleration would decrease as an object (matter) passed through the earth.

of course, the geometric center doesn't neccessarily imply the center of mass.

If we're talking pure hypotheticals here, then yes, the tennis ball would indeed be suspended at the center given a small amount of time. Let's not forget that a tennis ball doesn't have very much mass and therefore has an extremely low terminal velocity. Therefore, it would fall to the center of the earth and after a few passes back and forth, it would stop near the center and move about according to the tidal forces from the moon.

Of course this is purely hypothetical and therefore only as valid as one's personal opinion. =)

it will go in and go through and up to the other side but it will go up to the surface of the planet on the other side but over time the drag from the air will steel its gravity energy and it will be stuck in the middle of the earth

I tend to agree with what's been said, but I don't think the ball would come anywhere near the opposite surface of the planet.

I suppose it would reach terminal velocity, and as soon as it passed the dead centre gravity would begin working in reverse to bring it back down again. The best answer I can find with respect to the terminal velocity of a tennis ball is around 60mph, so the question then becomes, how high would a tennis ball go if you threw it straight upwards at 60mph?

The best baseball pitchers, I think, can throw at speeds of up to 100mph? So take 60% of that force, and that's pretty much what you're talking about.

So...in my humble opinion our hypothetical tennis ball would plummet to the centre of the Earth, pass the centre, and travel for maybe a few dozen metres before gravity took over and pulled it back, and it would quickly find itself 'hovering' at the centre of the planet.

This doesn't allow of course for any unseen anomalies sucking it into a parallel universe or monsters eating it that live at the centre of the Earth