astronomicalobservationsshowthatthecenterofmassoftheEarth-Moonsystemis4.7×10^6mfromthecenteroftheEarth.ThedistancebetweenthecentersoftheEarthandtheMoonis3.8×10^8m.(answerthisqueationinEnglish)1Findthemassofth

Question

astronomical observations show that the center of mass of the Earth-Moon system is 4.7×10^6m from the center of the Earth.The distance between the centers of the Earth and the Moon is 3.8×10^8m .(answer this queation in English)
1Find the mass of the Moon in terms of the mass of the Earth M(E)
2Explain why both Earth and Moon must rotate about their coomon center of mass rather than the moon about the center of mass of the Earth.
是question 不是queation
common center 不是coomon

Answer 1

Both Earth and Moon must rotate about their common center of mass rather than the moon about the center of mass of the Earth is because of Law of universal gravitation.
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.