Every day, when the earth rotates, it goes upside down. So, why don't we fall off?
Please give a simple clear explanation.
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answers:
Jim Moor say: Actually...
Not only are we going 1000 mph around, we are also going:
66,000 miles per hour as we yearly go around the sun, but also:
483,000 miles per hour as the sun orbits the milky way!!!!
Anyone feel like we're going to be flung out to space any second????
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Ian H say: Yes, imagine those poor people in Australia and New Zealand hanging on by their fingernails! Of course that does not happen because earth's gravity acts towards the centre of the earth, not towards some imagined off- earth down direction. But perhaps you meant why is it, with the surface of the earth spinning at about 1040 mph do we not get thrown off in the way that stuff does tends to fly off of spinning objects ?
There IS some upward force due to this effect, (and others), and we experience a balance of such forces. The overall effect is that for every kilogram of your weight, your body experiences a resultant downward force of approximately 9.81 Newtons/kilogram. There are slight variations at different locations around the earth.
One cause is that the earth is not a perfect sphere; it is ellipsoid, bulging out slightly at the equator. We calculate using g = GMm/r^2
So, because the surface is a greater distance away at the equator,
this reduces the g we experience there, but only slightly.
But let's return to how strong the reduction due to the spinning earth might be
The earth's radius R is about 6,371,000 metres and the surface rotational speed v of 1040 mph is about 465 m/s, so we can calculate the reduction in g downwards due to centripetal acceleration as