What Happens When a Pebble is Dropped Through Earth's Core?

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In summary: But you are neglecting the considerable air resistance. So it will not be close to SHM in the beginning.
  • #1
nami habib
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if a tunnel is bored through the centre of the Earth and a pebble is dropped into it then the pebble will do what ?...A)stop at centre...b)perform s.h.m.
 
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  • #2
SHM for a considerable period of time, given that it would have gained enough momentum to defy gravity and travel to the other end of the hole by the time it reaches the centre. And then gravity pulls it right back.[EDIT: And that's if the hole is drilled from pole to pole.]
 
  • #3
vhbelvadi said:
SHM for a considerable period of time, given that it would have gained enough momentum to defy gravity and travel to the other end of the hole by the time it reaches the centre. And then gravity pulls it right back.[EDIT: And that's if the hole is drilled from pole to pole.]

But you are neglecting the considerable air resistance. So it will not be close to SHM in the beginning.

I'm of course assuming that molten rock/metal will not refill the hole when the drill is removed...
 
  • #4
Assuming the tunnel was bored through a perfectly spherical Earth and was in a vacuum then it would SHM for quite a while if not indefinitely.
 
  • #5
nami habib said:
if a tunnel is bored through the centre of the Earth and a pebble is dropped into it then the pebble will do what ?...A)stop at centre...b)perform s.h.m.
IF you are ignoring air resistance then you will have harmonic motion- just as vhbelvadi says. Energy will be conserved so the pebble will accelerate until it reaches the center of the earth, decelerate so that it stops just as it reaches the surface at the other end of the tunnel, then repeat its motion.

IF you are not ignoring air resistance, then Energy is not conserved. Depending upon just how much energy is lost to friction, the pebble may perform "damped" harmonic motion for several repetitions, eventually stopping at the center of the earth, as torquil says.
 
  • #6
thnx guys
 
  • #7
I was just wondering, if the hole drilled has a radius that is considerably small and we assumed a vacuum (so there's no question of air resistance) and the hole was drilled along the equatorial plane, would the pebble actually reach the other end at all or would it strike an inner wall of the hole because the Earth would have rotated quite a distance by that period of time?

(I reckon it would take the pebble about 19min to reach the centre so roughly double to reach the opposite end of the tunnel which means the Earth would have moved thousands of metres by then.)
 

1. What is the Earth's core made of?

The Earth's core is primarily made up of iron and nickel, with smaller amounts of other elements such as sulfur and oxygen.

2. How deep is the Earth's core?

The Earth's core is divided into two layers: the inner core, which is solid and has a radius of about 1,220 kilometers, and the outer core, which is liquid and extends to a depth of about 2,890 kilometers.

3. What happens to a pebble when it is dropped through the Earth's core?

As the pebble falls through the Earth's core, it will experience increasing pressure and temperature. At the boundary between the outer and inner core, the pebble will reach a temperature of about 5,400 degrees Celsius and a pressure of about 3.6 million times the pressure at the surface. The intense heat and pressure will cause the pebble to melt and eventually disintegrate.

4. Can a pebble make it through the Earth's core?

No, a pebble would not be able to make it through the Earth's core. As mentioned earlier, the intense heat and pressure would cause the pebble to melt and disintegrate. Additionally, the Earth's core is made up of molten iron and nickel, which would act as a barrier to any solid objects passing through.

5. What would happen to the pebble's remains after passing through the Earth's core?

After passing through the Earth's core, the pebble's remains would continue to fall towards the center of the Earth due to gravity, eventually reaching the inner core. Here, the temperature and pressure are even higher, causing the pebble's remains to completely melt and become a part of the molten core. It would take millions of years for the pebble's remains to reach this point, as the inner core is about 5,000 kilometers below the surface.

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