# Earth's Rotation

• skepticsm

#### skepticsm

I have a question about the centripetal acceleration required for Earth's rotation about its axis. There obviously must be a force causing this acceleration, but I can't seem to figure what the source of this force is. Anyone happen to know the answer?

## Answers and Replies

For any piece of the Earth not on the axis of rotation there will be a net centripetal force. Gravity and contact forces (from surrounding material) provide the radial force, the net of which is towards the axis of rotation.

Hi,
Regarding the Earth as simple solid body, no outer force is required for spinning of the Earth by the conservation law of angular momentum.
Regarding the Earth as complex of parts, part of gravity to the center of Earth works as centripetal force to keep them not dispersed.
Regards.

Skepticsm, centripetal acceleration is in the radial direction, but the earth’s rotational motion is in the tangential direction. As such, centripetal acceleration does not cause the earth’s rotation--I am taking the Earth's radius to be a constant here. Did you mean to ask: what torque acts upon the Earth to cause its rotation?

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I have a question about the centripetal acceleration required for Earth's rotation about its axis. There obviously must be a force causing this acceleration, but I can't seem to figure what the source of this force is. Anyone happen to know the answer?
Rain.