What will happen to our motion when the Earth stops suddenly?

Discussion in 'Physics & Math' started by Saint, Jan 30, 2020.

  1. Saint Valued Senior Member

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    What will happen to our motion when the Earth stops suddenly?
    If the Earth suddenly becomes static, not revolving around its axis, not revolving around the Sun,
    at that instant, what will happen to us?
     
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  3. billvon Valued Senior Member

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    You asked two different things.

    What if the Earth suddenly stops rotating? Then you would find yourself flung through the air towards the East at between 300 and 1000mph as the Earth stopped and you kept going. Followed by the oceans, the lakes, the atmosphere, basically anything not attached to the earth.

    What if the Earth suddenly starts orbiting the Sun? If you are on the "front" of the Earth (the side facing the direction of travel) at that point you would be flung upwards into space at 66,000 miles per hour, which is enough to permanently leave the Earth and head out into space. If you are on the "back" of the Earth at that point the Earth would smash you flat as it hit you at 66,000 mph.
     
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  5. spidergoat Liddle' Dick Tater Valued Senior Member

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    Least of our problems at that point.
     
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  7. Saint Valued Senior Member

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    How about it takes some time for the Earth to become static?
    The earth reducing its angular momentum slowly until zero.
    What will happen to us?
     
  8. billvon Valued Senior Member

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    If it's very slowly? There was another thread on this. Short answer is that one side gets very hot and one side gets very cold. You _might_ be able to live in the twilight zone. But it would not be pleasant.
     
  9. Saint Valued Senior Member

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    how about the Earth instantly reverse its rotation direction?
     
  10. Jeeves Valued Senior Member

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    By the time it was going the other way, nothing would matter to you.
     
  11. Saint Valued Senior Member

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    When the Earth reverses its rotation direction, does it mean we go back to tomorrow?
     
  12. billvon Valued Senior Member

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    Then you are instantly dead.
    Nope. We don't go into any tomorrows. We are all dead.
     
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  13. Jeeves Valued Senior Member

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    That's pretty much the bottom line of any version of this hypothetical:
    You are dead.
     
  14. Saint Valued Senior Member

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    We won't be dead, the clock will run opposite.
     
  15. sideshowbob Sorry, wrong number. Valued Senior Member

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    The rotation of the earth does not control time.
     
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  16. Jeeves Valued Senior Member

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    You will be dead. You will not be older or younger, just space flotsam.
    Your clock will be space flotsam. If it didn't stop from the Big Jolt, it will when the battery runs down, and the aliens who find it floating past Titan won't be able to tell which direction it had been running - or what it had been used for.
    Maybe they'll enshrine it in a Tita-nut shell; maybe it'll start a cargo cult.
    But you'll be dead.
     
  17. (Q) Encephaloid Martini Valued Senior Member

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    Did you get that idea from the Superman movie?
     
  18. Janus58 Valued Senior Member

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    No, it won't. While it was convenient to have a unit of time measurement based on the period of the Earth's rotation* , the Earth's rotation doesn't act as the source of time flow.(In fact, once we determined that the rotational speed of the Earth was not constant, we switched our basis for the second to something that was constant. And because our clocks are no longer tied directly to the Earth's rotation, they slowly drift apart. Again for mere convenience sake, we don't want our clocks to drift too far from the day-night cycle. So we will, on occasion, adjust our official civil time by adding a "leap second". The last leap second was added Dec 31, 2016.)

    * the 24 hour "Solar" day actually relies on a combination of the Earth's orbital motion and its rotation. The Earth takes ~ 23 hr and 56 min to complete one rotation. However, during that time the Earth also travels something in the order of 1 degree in its orbit around the Sun, so it takes that extra 4 mins for the Earth to line back up with the Sun in the same way (to go from noon to noon). If the Earth were rotating in the opposite direction, then the solar day would be ~ 8 min shorter than it is now, and there would be 367.3 days to a year.

    In addition, the actual solar day varies by nearly 1 min over the course of the year due to the fact that the Earth's orbital speed changes over it's orbit. However, we really don't worry about this in terms of adjusting our clocks, as it is a periodic change and not accumulative.
     
  19. billvon Valued Senior Member

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    Imagine a car is driving at 90mph, and someone pushes you out the door. You will either die, or wish you were dead - you will be hitting a road at 90mph, and either the various decelerations will kill you (broken back, neck, skull etc) or you will abrade much of your body away as you slide.

    Now imagine that happening as the car is moving at 1400mph. And not on a smooth road - over a dirt trail. That's what it will be like. You will die almost instantly. If somehow you do not die, time will proceed normally - but you will see the sun rise in the west
     
  20. Saint Valued Senior Member

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    Is the Earth running slower or faster in her own rotation and revolution around the Sun?
     
  21. billvon Valued Senior Member

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    The Earth's rotation is slowly slowing down. The Sun is also getting lighter, and thus its gravity is decreasing - and we are moving away from it.
     
  22. Beaconator Valued Senior Member

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    I think its slowing down at the rate of which we will need an extra day in our leap year in about 100,000 years if I remember correctly.
     
  23. Janus58 Valued Senior Member

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    The Earth's rotation is slowing due to tidal interaction with the Moon; increasing it period of rotation by 1.7 milliseconds/century.
    The Earth's orbit around the Sun is a bit more complicated, and its net movement depends on the time period over which you are measuring the change.
    Over the next billions of years, it will slow as it moves away due the the aforementioned loss of mass from the Sun.
    When the Sun begins to expand into a Red giant, drag from the expanded Solar atmosphere will likely cause it to drift back in for a while.
    Over smaller time periods, it can migrate either in or out by a bit.
    For instance, according to these tables from JPL:
    https://ssd.jpl.nasa.gov/txt/p_elem_t1.txt
    https://ssd.jpl.nasa.gov/txt/p_elem_t2.txt
    In the time period 1800AD-2050AD, the Earth is expected to have a net movement away from the Sun, but for the time period of 3000BC-3000AD, It has a slight net inward movement towards the Sun.
     

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