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Question
Both earth and moon are subject to the gravitational force of the sun. As observed from the sun, the orbit of the moon ______.
Options
will be elliptical.
will not be strictly elliptical because the total gravitational force on it is not central.
is not elliptical but will necessarily be a closed curve.
deviates considerably from being elliptical due to influence of planets other than earth.
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Solution
Both earth and moon are subject to the gravitational force of the sun. As observed from the sun, the orbit of the moon will not be strictly elliptical because the total gravitational force on it is not central.
Explanation:
The moon revolves around the earth in a nearly circular orbit. When it is observed from the sun, two types of forces are acting on the moon one is due to gravitational attraction between the sun and the moon and the other is due to gravitational attraction between the earth and the moon. So the moon is moving under the combined gravitational pull acting on it due to the earth and the sun. Hence, the total force on the moon is not central.
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