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Author Topic: Why don't people fall off the bottom of the Earth?  (Read 8995 times)

Offline Shaun Rensburg

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Shaun Rensburg  asked the Naked Scientists:
   
Hello Chris
 
My question. If the Earth is round, we do we at the bottom not fall off, and we are we not standing upside down?
 
Regards
 
Shaun Rensburg

What do you think?
« Last Edit: 12/01/2011 16:30:02 by _system »


 

Offline Bill S

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Why don't people fall off the bottom of the Earth?
« Reply #1 on: 13/01/2011 02:31:02 »
Hi Shaun,

If this is a serious question, perhaps you should start by defining what you understand by "top" and "bottom" of the Earth.  :)
 

Offline CliffordK

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Why don't people fall off the bottom of the Earth?
« Reply #2 on: 13/01/2011 03:32:38 »
The question should be why people don't fall off of the equator, rather than the north and south poles.

The gravity is actually strongest at the two poles...  and, excluding mountains & snow, the distance to the center of the earth is least at the two poles. 

You are always attracted to the center of the earth.  So, from wherever you are on earth, "down" is towards the center of the earth. 

There is an effect of centrifugal force that makes people lighter at the equator (still true elsewhere, but to a lesser extent at other latitudes).  But the earth isn't spinnning fast enough to actually cause people to fly off.
 

Offline Geezer

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Why don't people fall off the bottom of the Earth?
« Reply #3 on: 13/01/2011 06:00:17 »
There is an effect of centrifugal force that makes people lighter at the equator

Oh no! Here we go again!  ;D

There is no centrifugal force acting to push people away from the surface of the earth. However there is a centripetal force required to keep them rotating with the surface of the Earth.

Weight is a measure of the reaction between a body and gravity, and that reaction acts in a direction radially outwards from the centre of the earth. The centripetal force acts towards the centre of the Earth, although in this case it's quite small, so the net effect is to reduce the reaction to the force of gravity i.e., the weight, slightly. 

 

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Offline Foolosophy

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Why don't people fall off the bottom of the Earth?
« Reply #4 on: 13/01/2011 06:54:49 »
Shrunk
There is an effect of centrifugal force that makes people lighter at the equator

Oh no! Here we go again!  ;D

There is no centrifugal force acting to push people away from the surface of the earth. However there is a centripetal force required to keep them rotating with the surface of the Earth.

Weight is a measure of the reaction between a body and gravity, and that reaction acts in a direction radially outwards from the centre of the earth. The centripetal force acts towards the centre of the Earth, although in this case it's quite small, so the net effect is to reduce the reaction to the force of gravity i.e., the weight, slightly. 



So what you're saying is that the Earth's Weight is equal to zero
 

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Offline Geezer

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Why don't people fall off the bottom of the Earth?
« Reply #5 on: 13/01/2011 06:57:20 »
Shrunk
There is an effect of centrifugal force that makes people lighter at the equator

Oh no! Here we go again!  ;D

There is no centrifugal force acting to push people away from the surface of the earth. However there is a centripetal force required to keep them rotating with the surface of the Earth.

Weight is a measure of the reaction between a body and gravity, and that reaction acts in a direction radially outwards from the centre of the earth. The centripetal force acts towards the centre of the Earth, although in this case it's quite small, so the net effect is to reduce the reaction to the force of gravity i.e., the weight, slightly. 



So what you're saying is that the Earth's Weight is equal to zero

I don't think so. How did you come to that conclusion?
 

Offline Don_1

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Why don't people fall off the bottom of the Earth?
« Reply #6 on: 13/01/2011 10:16:34 »
It is rather perplexing that we consider the northern hemisphere to be the 'top' of the world and the southern to be 'down under'. Does this mean that when Bruce puts his can of neck oil on the bar to go to relieve his pyjama python, he puts it upside-down?
 

Offline yor_on

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Why don't people fall off the bottom of the Earth?
« Reply #7 on: 13/01/2011 11:58:32 »
Shaun I know what you mean and I will answer in the manner you asked. I think it has to do with that we all got it wrong, as proven again and again through countless years the Earth should be flat. At least on the 'small scale', just as our universe seems to be. In fact I have a suspicion we all are so called 'flat landers', not that it surprise me. And so we solve the puzzle :) No oil spilled.
==

Just don't lean to far over the edge...
 

Offline CliffordK

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Why don't people fall off the bottom of the Earth?
« Reply #8 on: 14/01/2011 00:01:04 »

There is no centrifugal force acting to push people away from the surface of the earth. However there is a centripetal force required to keep them rotating with the surface of the Earth.

Sorry...  I should have specified better...
The acceleration due to the tendency to follow a straight line of motion (Newton's First Law) and the acceleration component due to a divergence from this straight line.
 

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Why don't people fall off the bottom of the Earth?
« Reply #8 on: 14/01/2011 00:01:04 »

 

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