Question

The Sun’s attraction of both earth and moon are external forces acting on the centre of mass of the earth-moon system.

(a) True

(b) False

I have been asked this question in an international level competition.

I'd like to ask this question from Forces and Inertia in chapter Gravitation of Engineering Physics I

Answer 1

Right answer is (a) True

To explain I would say: The moon moves around the earth in a circular orbit and the earth moves around the sun in an elliptical orbit. Here the mutual force of gravitation between the earth and the moon are internal forces while the Sun’s attraction of both earth and moon are the external forces acting on the centre of mass of the earth-moon system.