Is the gravitational acceleration we consider only the attraction due to the Earth's gravity or is it that of gravity plus the attraction due to Earth spinning?

We know that earth produces an acceleration towards the centre on any body near it due to gravitational attraction.

We denote this acceleration as $g$.

But we also know that any body on Earth is also undergoing rotational motion due to earth's Spin. So every body should experience an outward centrifugal acceleration.

Does acceleration due to gravity $g$ take the centrifugal acceleration into consideration?

  • $\begingroup$ I didn't understand what do you mean by $\textit{"attraction of earth's gravity"}$. However, we consider $g$ only due to interaction between earth and body. $\endgroup$
    – SarGe
    Commented May 14, 2020 at 4:18
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    $\begingroup$ Have you calculated whether it makes much difference? $\endgroup$
    – G. Smith
    Commented May 14, 2020 at 4:23
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    $\begingroup$ The centrifugal pseudoforce acts outward, not inward. $\endgroup$
    – Sandejo
    Commented May 14, 2020 at 5:53

2 Answers 2


$g$ is measured by observing the freefall acceleration of objects in a vacuum. Since this is taking place in the non-inertial, rotating reference frame of the Earth's surface, it does include the centrifugal effects on acceleration. However, it is also worth noting that this effect is generally not very large: $g\approx 9.8 \ \mathrm{m/s^2}$ across the Earth, while at the equator (where centrifugal acceleration is greatest) the centrifugal acceleration is given by $a_c=\left( \frac{2\pi}{1 \mathrm{day}} \right)^2 R_{\oplus,\mathrm{eq}} = 0.0337 \ \mathrm{m/s^2}$, where $R_\oplus$ is the equatorial radius of the earth.

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    $\begingroup$ FWIW, Google Calculator can easily do this: (radius of earth)*(2*pi/(1 day))^2 $\endgroup$
    – PM 2Ring
    Commented Nov 22, 2020 at 6:04

g is caused only by earth gravitational pull. While centripetal acceleration is an acceleration caused by centripetal force. Centripetal force is a net force of a body that undergoes circular motion.

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    $\begingroup$ I think his question is that any body on earth is also undergoing rotational motion due to earth's spin. Also any body undergoing Rotational motion experiences a centre seeking (centripetal) acceleration. So when we talk about 'Acceleration due to gravity' , does it accounts for the centripetal acceleration of earth's spin ? $\endgroup$
    – Jdeep
    Commented May 14, 2020 at 4:57
  • $\begingroup$ This answer is incorrect. Geophysicists distinguish between gravity and gravitation. Earth gravitation accounts only for the Newtonian attraction between the Earth's mass and some other object. Earth gravity ($g$) adds centrifugal acceleration to the mix. $\endgroup$ Commented Apr 16, 2021 at 11:07

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