How Does Your Weight Change from the Poles to the Equator?

[georgert]

If I have a mass of 80 kg, what would the difference in my weight be at either the North or South Pole and at the equator? It would seem to me that the spin of the Earth would induce a centrifugal effect that would counter somewhat Earth's gravitational pull at the equator, but not do so at Earth's axis of spin.

 

[arildno]

If I have a mass of 80 kg, what would the difference in my weight be at either the North or South Pole and at the equator? It would seem to me that the spin of the Earth would induce a centrifugal effect that would counter somewhat Earth's gravitational pull at the equator, but not do so at Earth's axis of spin.

That's absolutely correct.
The effects of having an equatorial bulge and flattened poles also contributes to variation of the local value of "g", compared to what you'd get by a strictly spherical shape.
"g" is also slightly dependent upon density variations.


According to Wikipedia, the local values of "g" are as follows:

local gravity, g, increases from 9.789 m·s−2 at the equator to 9.832 m·s−2 at the poles.[1]

 

[astrokreng]

I can confirm that there is indeed a difference in weight at different locations on Earth due to the effects of gravity and the centrifugal force. At the North and South Pole, where the axis of rotation of the Earth is located, the centrifugal force is minimal and therefore the weight of an 80 kg person would be approximately 80 kg. This is because the gravitational force is the dominant force at these locations.

However, at the equator, the centrifugal force is at its maximum due to the Earth's rotation, which causes the Earth to bulge slightly at the equator. This bulge creates a slightly larger distance between the center of mass of the Earth and a person standing on the surface, resulting in a weaker gravitational force. Therefore, an 80 kg person at the equator would weigh slightly less than 80 kg due to the counteracting effects of the centrifugal force.

The exact difference in weight between the equator and the poles would depend on the Earth's rotation rate and the person's distance from the center of the Earth. Nonetheless, the difference would be very small and would not be noticeable to an individual.

It is important to note that the effects of gravity and the centrifugal force are not the only factors that determine a person's weight. Other factors such as altitude and the density of the material beneath a person's feet can also play a role. Additionally, a person's weight also varies due to the Earth's non-uniform shape and its varying density, which causes slight variations in gravitational pull at different locations on Earth.

In conclusion, while there is a difference in weight at the equator and the poles due to the effects of gravity and the centrifugal force, it is a very small difference and would not significantly affect an individual's weight.