Relative Motion and Flight ```Name: Steven G. Status: student Age: 14 Location: N/A Country: N/A Date: 2001-2002 ``` Question: We are studying forces in science class. If you were in plane traveling 806 mph in the opposite direction of the Earth's rotation, would the sun never move? Replies: If you were at 40 degrees latitude this would be true. At the equator, you'd have to travel at around 1050 mph. Tim Mooney Steven, Actually, the sun doesn't move much anyway. It is the Earth's surface that really moves, rotating around once per day. By flying as you suggest, you are causing the plane to "STOP" moving. You are making the plane stay aligned with the sun. You are correct: you would never see the sun rise or set. Dr. Ken Mellendorf Physics Instructor Illinois Central College I am not sure that 806 mph is the correct speed, because it would depend upon latitude, but the principle is correct. If you moved at the same speed as the earth is moving about its axis with respect to the Sun, the Sun would just "hang there". Vince Calder I do not recall the exact figures for the earth's circumference at the equator but this number seems a little low to me. Of course, the speed required would depend on your latitude as well. At the equator you would have to fly much faster than if you were close to one of the poles. Without dealing with the exact numbers, if you matched the earth's rotational speed and flew in the opposite direction for one year the earth would rise and set one time (as the earth moved around the sun). Greg Bradburn Click here to return to the Physics Archives

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