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I know it's a regular question, but I'm having a problem with the concept of circular motion.

Intuitively, the earth and people have the same angular velocity,It's because people are standing on the earth. It looks like a centripetal force provided by a component of universal gravitation, not because of friction.

I don’t want to understand through intuition, I know that we can find the centripetal force by knowing the angular velocity, which is the cause of synchronization. But I want to understand from the perspective of force, not speed.

If a person jumps up, it will maintain the same linear velocity. Because the component force of gravitation will perform a circular motion. And this axis of circular motion is also the axis of the earth’s rotation.

I know the reason why man and the earth rotate together, but this is derived from phenomena. Because of this, I say it is due to the component force provided by gravity. If you don’t explain this phenomenon, why does universal gravitation always provide a centripetal force, which happens to be at the same speed as the earth?

Why is this speed moving in a circular motion around the axis of the earth's rotation?I know that in a circular motion, the speed is perpendicular to the force,Why is the axis of circular motion between this linear velocity and gravitation not redefined?

What is the reason that the circular motion of the object when it leaves the surface of the earth still maintains the same axis as the rotation of the earth?

The main problem is here

Ⅰ Through observation of the phenomenon, we can know that it is because of the centripetal force provided by universal gravitation.Why does this centripetal force provide the same speed effect as the earth's rotation speed.Can I explain without phenomenon.

Ⅱ If you leave the surface of the earth,I don’t know how it will be. Suppose that gravitation provides a component perpendicular to the direction of velocity,Make a circular motion.Whether the rotation axis of circular motion is the same as the rotation axis of the earth.Because gravitation provides a component force perpendicular to speed, this direction is uncertain. There are many possibilities.

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  • $\begingroup$ why does gravitation always provide a centripetal force, which happens to be at the same speed as the earth? What exactly do you mean by this? $\endgroup$ – Deschele Schilder Aug 22 '20 at 7:36
  • $\begingroup$ Why is this speed moving in a circular motion around the axis of the earth's rotation? How a speed can move? $\endgroup$ – Deschele Schilder Aug 22 '20 at 7:38
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    $\begingroup$ You ask many questions at one time. What is that basic question? $\endgroup$ – Deschele Schilder Aug 22 '20 at 7:40
  • $\begingroup$ Through observation of the phenomenon, we can know that it is because of the centripetal force provided by universal gravitation.Why does this centripetal force provide the same speed effect as the earth's rotation speed.I am sorry for my poor English。 $\endgroup$ – 能够可能 Aug 22 '20 at 7:41
  • $\begingroup$ Aah, don't mind your Englisch. I can understand. Do you think the force of gravity (the centrifugal* force decreases the force of gravity by a small amount) provides a speed? And to whom this force gives speed is given? Actually, a force gives acceleration; which of course also implies speed is provided. Do you mean a constant speed? $\endgroup$ – Deschele Schilder Aug 22 '20 at 7:56
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The rest frame of a point on the surface of earth is only appropriately inertial. The non-inertial character is accounted for by the Coriolis force and the centrifugal force. In case of non-constant rotation ty here usxaksi the Euler force. See https://en.m.wikipedia.org/wiki/Coriolis_force

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  • $\begingroup$ It's too hard for me,If you don’t consider this factor.Why are objects in the sky affected by the rotation of the earth,Why is universal gravity not regarded as all gravity.The centripetal force can only be observed through phenomena? $\endgroup$ – 能够可能 Aug 22 '20 at 8:58
  • $\begingroup$ Objects in the sky are not affected by the rotation of the Earth. You, the observer standing on Earth, are. If you interpret what you see as if you were in an inertial frame, that is without accounting for your own rotation, then it appears that external objects feel fictitious forces. $\endgroup$ – my2cts Aug 22 '20 at 10:09

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