Gravitational Field: What Would Happen?

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Discussion Overview

The discussion revolves around the hypothetical scenario of the Earth slowly stopping its rotation while maintaining its gravitational field. Participants explore the implications of this scenario on objects at the Earth's surface, considering both the physical effects and the perceptibility of such changes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that if the Earth lost angular momentum slowly, it might not be noticeable to people.
  • Others question what level of deceleration would be humanly noticeable, with references to experiences during earthquakes.
  • One participant proposes calculating the centripetal force acting on an object at the equator to determine if the change would be noticeable compared to gravitational force.
  • There is a mention of using SUVAT equations to analyze the conditions under which the Earth's rotation could be brought to a halt without catastrophic effects.
  • Some participants note that the Earth's rotation is indeed slowing, but interpretations of what constitutes "noticeable" vary.
  • Speculation arises about the potential ocean currents resulting from even minor changes in gravitational effects.

Areas of Agreement / Disagreement

Participants express differing views on what constitutes a "noticeable" change in the context of the Earth's rotation slowing. There is no consensus on the specific deceleration that would be perceptible to the average person.

Contextual Notes

Limitations include the lack of specific mathematical calculations presented and the dependence on subjective interpretations of "noticeable." The discussion also does not resolve the feasibility of such a scenario occurring.

LeoPedranjo
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Hi guys!

What would happen to objects on the Earth's surface if it SLOWLY stopped spinning and Earth's gravitational field was kept as always.

Thx
 
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Hi welcome to PF

what do you think would happen ?
consider the difference of when you are in a car that stops quickly or slowlyDave
 
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davenn said:
Hi welcome to PF

what do you think would happen ?
consider the difference of when you are in a car that stops quickly or slowlyDave

Considering Earth's dimension, if it lost the angular momentum slowly due to somenthing we woundn't notice, right?
 
correct ...

Im not sure of the maths offhand, maybe some one else can chime in and
give info on how slow the deceleration would be before it wasn't noticeable
 
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davenn said:
c
Im not sure of the maths offhand, maybe some one else can chime in and
give info on how slow the deceleration would be before it wasn't noticeable
The Earth's rotation is slowing and we have noticed.
 
Yeah, different meanings of "noticeable". :)
 
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jbriggs444 said:
The Earth's rotation is slowing and we have noticed.

indeed as with good instruments

nasu said:
Yeah, different meanings of "noticeable". :)

uh huh
so I wonder what would be the necessary deceleration to be humanly noticeable to the avg person ?

0.2 - 0.5g is easily noticeable with earthquake motion
 
davenn said:
so I wonder what would be the necessary deceleration to be humanly noticeable to the avg person ?

0.2 - 0.5g is easily noticeable with earthquake motion
Can you imagine the kind of ocean current you could get from something as tiny as 0.01 g? Goodbye, California.
 
LeoPedranjo said:
What would happen to objects on the Earth's surface if it SLOWLY stopped spinning and Earth's gravitational field was kept as always.
The centripetal force needed to keep an object of mass m on a circular path of radius r and at a speed v is given by F = mv2/r
Put in the numbers for an object of 1kg on the Earths Equator and the speed (all that data is readily available) and you can calculate the force. Compare that with the weight force (approximately 10N per kg) and that will tell you whether or not we would "notice" it. It will relate to the difference in the Weight of an object at the N Pole and at the Equator.

You could also, using the SUVAT equations, find out how quickly you could bring the Earth's rotation to a halt if you wanted the effect to be 1. Noticeable and 2. low enough so that things don't go flying off the table or buildings topple over. You can make up your own numbers for the acceleration (negative acceleration, of course) for those two conditions i.e how much g force?

It's just as well that it's not an experiment that we could ever do. If it were possible then some damned fool could just possibly try it. :))
 

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