my mate is having a discussion about the core of the earth. he seems to believe that the core of the earth is empty. his reasoning, a tumble dryer, when it spins there is an empty space. he wont believe anything e.g. molten iron etc that science has taught. he says its only a theory. someone tell me how these theories were found.
core of earth
- Thread starter Burly
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Well, the tumble dryer is using centrifugal (centripedal?) force to hold the clothes onto the outside of the drum.
If the earth were spinning fast enough for the molten rock to stick to the crust and leave an air filled hole in the centre, we'd all have flung off into space long ago.......
If the earth were spinning fast enough for the molten rock to stick to the crust and leave an air filled hole in the centre, we'd all have flung off into space long ago.......
Centrepetal acceleration (force) 
Centrifugal force technically doesn't exist.
The earth's core is solid. We know that because when there's an earthquake, we can measure the changes to the vibrations as they bounce around inside and get picked up by listening stations on the surface. There is no evidence to suggest it's anything but a solid lump of mostly iron.
If your 'mate' wants to believe some other theory, he's perfectly free to do so. I suspect conspicary-theory-like-wanting-to-get-laid-by-sounding-interesting-different-and-controversial syndrome again.
Centrifugal force technically doesn't exist.The earth's core is solid. We know that because when there's an earthquake, we can measure the changes to the vibrations as they bounce around inside and get picked up by listening stations on the surface. There is no evidence to suggest it's anything but a solid lump of mostly iron.
If your 'mate' wants to believe some other theory, he's perfectly free to do so. I suspect conspicary-theory-like-wanting-to-get-laid-by-sounding-interesting-different-and-controversial syndrome again.
growse said:Centrepetal acceleration (force)
http://www.merriam-webster.com/dictionary/centrifugal force
Dictionary seems to contradict you.
http://www.britannica.com/eb/article-9022100/centrifugal-force
Centrifugal force is the opposite of centripetal. Centripetal is what holds a spinning object in (like mavity does to the moon around the earth), while centrifugal force is what keep the moon from crashing into the earth.
Associate
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Then the writers of the dictionary never took A Level physics...there is no centrifugal force, if you swing a ball on string around the only force is the centripetal force of the string pulling the ball to the centre and preventing it from carrying on ina straight line
He is actually right - "centrifugal force" does NOT exist. It is actually a reaction to centripedal force that you feel. All objects rotating about a point feel an acceleration towards that point. Since they are accelerating then they must be subject to a force pulling them to the centre, which is centripedal force. But if the object is you in, say, a fairground ride, what is actually happening is the object you are on is accelerating towards the centre and pressin against you. This is because your body wants to go in a straight line, not towards the centre of rotation. Your body interprets that force inwards as your body trying to accelerate outwards and calls it centrifugal force, but it's just your brain misunderstanding what is going on.
M
M
Don't bother answering, I'm out of this thread.Mickey_D said:
mainly due to badly written sci fi programs / books of the 1950`s and 60`s p.s. to the original poster, tell your friend if he believes that the core is hollow then he may as well also believe in the easter bunny and noah`s ark as they all make an equal ammount of sense.
We can work out the internal structure of the earth when an earthquake happens. The earth "rings" like a bell as the seismic waves propagate out from the epicentre. By "listening" to how these waves are deflected inside the earth, using seismographs we detect the presence of layers, and a very dense solid object at earths centre.
We also can infer the presence of an iron core due to Earth's magnetic field. The field must be being produced by a substantial mass of iron somewhere deep below. In fact, it's the liquid outer core that is responsible for this.
We also can infer the presence of an iron core due to Earth's magnetic field. The field must be being produced by a substantial mass of iron somewhere deep below. In fact, it's the liquid outer core that is responsible for this.
i wish people would only read wikipedia - there is centrifugal force, but there is a real one and a 'false' one that doesn't exist.
oh, and your friend is an idiot - the core is made of iron - ask him where he thinks the earths very strong magnetic field comes from - is it magic??
oh, and your friend is an idiot - the core is made of iron - ask him where he thinks the earths very strong magnetic field comes from - is it magic??
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I'd rather read a physics book than Wilkipediea to get my facts straight to be honest.
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What exaxtly would the core fill with? Dissolved gases from nearby rocks? I think your friend is a bit of a numpty.
Ok, after quite a bit of research, I've come up with a layman's description here.
Picture yourself standing in one spot swinging a pail full of water on the end of a rope.
Centripetal force would be the force required by you to hold the bucket in a circle. Not the force pulling against you, the force you are exerting. Hence why it is almost always measured in pounds or kilograms.
Centrifugal force is the force apparent at the bucket. It is the force pulling the bucket and its contents to the horizontal plane away from you. It simulates an artificial means of mavity, hence why it is almost always measured in G's.
They are equal and opposite to each other and are a result of the same thing, an object trying to fulfil Newton's laws of physics, but being restrained by (in this case) the rope. One is the restraining force, one is the escape attempt force.
Picture yourself standing in one spot swinging a pail full of water on the end of a rope.
Centripetal force would be the force required by you to hold the bucket in a circle. Not the force pulling against you, the force you are exerting. Hence why it is almost always measured in pounds or kilograms.
Centrifugal force is the force apparent at the bucket. It is the force pulling the bucket and its contents to the horizontal plane away from you. It simulates an artificial means of mavity, hence why it is almost always measured in G's.
They are equal and opposite to each other and are a result of the same thing, an object trying to fulfil Newton's laws of physics, but being restrained by (in this case) the rope. One is the restraining force, one is the escape attempt force.
That's almost right. Centripetal force is the force you are exerting on the bucket, as you say. The bit that's wrong is that you are saying centrifugal force is acting on the bucket. The true centrifugal force is the force exerted on you by the bucket. That's where the misconception about centrifugal force is. Most people think of it as a force trying to pull the bucket out of the circle, when in reality no such force is needed as things will naturally travel in a straight line.Mickey_D said:
Really it's no different to being in an accelerating car. It feels like there is a force pushing you back into your seat, when really it's the seat pushing forward on you.
Mickey_D said:
Apologies Mickey - didn't want to sound condescending. I'm just dredging up memories from my physics days. You're right when you say that centrifugal force is an apparent force. If you're being spun round something, you feel like you're being pulled towards the outside. In your frame of reference, there is a force doing this.
It's just when you draw the diagrams and other complicated stuff, which usually are taken in the stationary frame of reference, there is no force which is pushing you outwards, only one pulling you inwards.
Your example with the bucket is a good one, because (assuming a vacuum and complete absense of mavity) there is nothing keeping the bucket flying around you other than the force of you reigning it in. If that wasn't there, it'd fly off in a straight line. If you were sat in the bucket with your eyes closed, you'd just feel the reactive force to the side of the bucket, which would be pulling you round with it.