Wikibooks: Planet Earth/1e. Earth’s Motion and Spin
Nav = Earth’s Rotation Each Day = Right now as you are reading this your body is traveling at an incredibly fast speed through outer space. We can calculate one component of this speed by taking Earth’s circumference based on the ellipsoid model for the Earth’s dimensions which exhibits an equatoria...
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| Language: | English |
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| Online Access: | https://en.wikibooks.org/wiki/Planet_Earth/1e._Earth%E2%80%99s_Motion_and_Spin |
| Summary: | Nav = Earth’s Rotation Each Day = Right now as you are reading this your body is traveling at an incredibly fast speed through outer space. We can calculate one component of this speed by taking Earth’s circumference based on the ellipsoid model for the Earth’s dimensions which exhibits an equatorial circumference of 24 901.46 miles (40 075.02 km). The Earth completes a rotation around its axis every day or more precisely every 23 hours 56 minutes and 4 seconds. If you are located at the equator your velocity (speed combined with a direction) can be calculated by dividing 24 901.46 miles by 23 hours 56 minutes and 4 seconds which equals 1 040.45 miles per hour. Of course this depends on your latitude and decreases as you approach the poles. One way to imagine this rotation is if you have ever watched an old record album spin or a free spinning bike wheel. The central axis of the spinning album or wheel is stationary while the outer edges of the circle are traveling the circumference of the circle with each revolution the further you move from the center of rotation the quicker your speed. In other words the larger the wheel the faster the rotation and the more distance is covered per unit time. Early scientists such as were aware of this motion and were curious as to why we do not feel this motion on the surface of the Earth. If you imagine an ant crossing a spinning record album at the edges the ant would feel the fast motion as air zoomed by and the pull of a centrifugal force working to fling the poor ant off the spinning record album but as the ant crawled toward the center its feeling of motion would decrease. The same thing can be felt if you have ever been on a merry go round the closer you are toward the center the less you feel the motion of your spin. However on Earth we do not feel like we are traveling at over a 1 000 miles per hour at the Equator and standing still near the north or south pole. This bizarre paradox inspired to study motion and in the process discovered and the that govern how ... |
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