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Earth slowing down

  1. Jan 19, 2014 #1
    I was watching a documentary that examines what happens if the earth slowed to a halt in the span of 5 years.

    One point they didn't cover was that since the Earth is slowing down at a greatly accelerated pace, what would the people feel? How much apparent force would they feel acting on them?
  2. jcsd
  3. Jan 19, 2014 #2


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    Why won't you try and calculate the linear velocity due to Earth's rotation of a person standing on the equator(it's the highest there). It's as easy as dividing the equatorial circumference by the length of day in seconds.
    With that in hand, calculate the acceleration required to slow down to 0 m/s over five years( ##ΔV=aΔt## ). Compare the acceleration to e.g. the gravitational acceleration.

    Tell us what you think about the result.
  4. Jan 19, 2014 #3
    The earth rotates at one circumference per day, which is roughly 500m/s at the surface. If it takes 5 years to slow down to zero, then it must decelerate at 100m/s/year, which is about 0.000003m/s^2, or roughly 0.0000003g. That's not very much, and I suggest, given all the climatic change and geophysical/tidal effects i suspect might happen, would probably not be noticeable. Great episode though...
  5. Jan 19, 2014 #4
    It's not 500m/s at the poles.If you stood at one of the poles a short distance away,you would rotate around it at approx 1 metre a day.
    So if you walked from the equator to the pole it would give you a pretty good idea of what you would feel if the Earth slowed down to allmost a halt.
  6. Jan 19, 2014 #5
    Thats true. 500m/s is at the equator, which is the fastest linear velocity at the surface of the earth, and would therefore exhibit greatest linear deceleration should the earths rotation change. At the poles, you wouldn't notice any change, apart from the massive climatic apocalypse happening around you. I do wonder where all those exajoules of rotational energy end up though - presumably into moving whatever unseen body is slowing the earth...
  7. Jan 19, 2014 #6
    Just imagine yourself on a recent aircraft trip. Instead of taking a few minutes to land or take off, imagine it takes five years.
    Last edited: Jan 19, 2014
  8. Jan 19, 2014 #7


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    One has to wonder, where is all that angular momentum going? (It's conserved.)
    Ignoring the impossibility of it, it would have a huge effect on weather. Hurricanes spin CCW in the northern hemisphere and CW in the southern hemisphere because of the coriolis force. Without rotation, there's no coriolis force, so hurricanes would be greatly transformed.
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