On Jeopardy the other day they answered at what lattitude you way the least. The question was 0 degrees. Alex said it was because of the earth’s rotation. Is that true or is it just because the equator is further from the center of the earth’s mass?
Yeah, it’s true. The rotational velocity is highest there, so the tendency to be flung outward counteracts some of the gravity. That’s also why the whole planet is slightly thicker in the middle than at the poles.
Another reason wy you weigh less at the equator is that you are farther away from the center of the Earth. It may be that you are farther from the center at the equator than on the summit of Everest. I’d have to check.
Yes, I realize that. The furthest point from the center of the earth is Mt. Chimborazo, in Ecuador.
ETA: Oops, you were compraing the equator (presumably sea level) to Everest.
At sea level, you weigh about half of one percent less at the equator than at the poles. Roughly 65% of the difference is accounted for by rotation (centrifugal force), the other 35% by the fact that you’re farther from the center of the earth at the equator (because the earth isn’t spherical).
I’ll just note that if I place a scale on the ground at sea level and then fly an airplane at 30,000ft over the scale, I won’t weigh anything at all.
If you hop over the scale at one inch, it won’t register anything either.
You get a similar effect if you just stand next to the scale.
Would you weigh less at the peak of Chimborazo, which is 1 degree south, than at any point at 0 degrees latitude?
Actually, you might rank as a negative weight if you are over or near the scale, since you have your own gravitational attraction that pulls up on the top.
I’m not sure though, since even if you weren’t there, there would be air particles.
Also if you zero the scale and then eat it.
What if you put the scale on a treadmill?
Could we take the scale to the bottom of the Marianas Trench?
All these scale posts - something’s fishy!
No! There is no latitude at which a person weighs the least.
Rotational forces are a red herring, because the earth is elastic. Think about it–the substance of the earth is affected by the rotational forces as well. Any would-be deviations of the net “weight force” from a sphere shape are filled in by the earth.
For more detail, read about the Geoid.
From your link, “The geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth …” and “the geoid is by definition a surface to which the force of gravity is everywhere perpendicular.” but that isn’t the same as saying that people weigh the same everywhere on the geoid. The force of gravity is the gradient of the potential in the direction perpendicular to the geoid. There is no reason for this to be constant everywhere on the geoid.
I suppose I should provide a link. Here you go.
Are scale-er weapons for real?
We already did. We’ve done it 0! times.
To further understand why things don’t weigh the same everywhere on the geoid, consider a contour map. Two points on the same contour line are the same height, but they do not necessarily have the same slope. Height is analogous to potential, while slope is analogous to the strength of the gravitational field.