Timeline for In the time of the dinosaurs the Earth rotated once in 17 hours rather than about 24 hours, where did the rotational energy and angular momentum go?
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| May 2, 2015 at 19:34 | comment | added | David Hammen | That 17 hours is rather short for the length of day "in the time of the dinosaurs". That's the length of day about 2.45 billion years ago (Williams, "Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit," Reviews of Geophysics 38.1 (2000): 37-59.) | |
| May 2, 2015 at 17:26 | comment | added | user78939 | To the best of my recollection it was an exercise in a Physics text. Cutnel and Johnson or Halliday and Resnick or Serway and Faughn, they might have worked backwards. | |
| May 2, 2015 at 17:16 | comment | added | innisfree | where did you read 17 hours? | |
| May 2, 2015 at 17:11 | answer | added | Floris | timeline score: 4 | |
| May 2, 2015 at 16:44 | answer | added | ceillac | timeline score: 2 | |
| May 2, 2015 at 16:19 | history | edited | Qmechanic♦ |
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| May 2, 2015 at 16:18 | comment | added | CuriousOne | The energy went into tidal motion and the angular momentum is still there (minus small changes due to similar orbital angular momentum coupling to the sun and other planets). The mechanism is exactly what you said it is. You can look up the moment of inertia for the Earth and calculate the total angular momentum for both configurations - fast Earth rotation and a closer Moon vs. slower rotation today with a more distant Moon. | |
| May 2, 2015 at 15:57 | history | asked | user78939 | CC BY-SA 3.0 |