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Q:
How does the rotation of the earth affect the weight of a stationary object at sea level?
Does an object of the same mass have a different weight at the poles than at the equator due to the centripetal force? Indeed, would we all weigh more if the earth were not rotating?
- Keith (age 47)
UK
A:
Yup, the earth's rotation makes the weight of objects a little less at
the equator. Gravity pulls down, but the object needs to accelerate in
the downwards direction in order to stay in a circular path around the
Earth's rotational axis in order to stay on the Earth's surface as it
turns. The centripetal acceleration is about 3.39 cm/sec^2 at the
equator (I'm getting this number from the CRC Handbook of Chemistry and
Physics), which is about 0.35% the acceleration of gravity at the
surface of the earth, g. There is an additional lightening factor, in
that the Earth bulges a little bit outwards at the equator because of
its rotation, making objects on the surface just a tad farther away
from the center, also making them lighter.
Yup, we'd all weigh just a little more if the Earth were not rotating.
Tom J.
(published on 10/22/2007)
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