Answer to Question #69 in Astronomy | Astrophysics for Richard

Question

Can the Earth be taken for a material point in the calculation of:
a) the distance between the Earth and the Sun;
b) the path traversed by the Earth in its orbit around the Sun over a month;
c) the length of the the Earth's equator;
d) the speed of the equator's point with the earth's daily rotation around the axis;
e) the speed of the Earth in its orbit around the Sun?

Answer 1

a) Yes, it can. The distance from the Earth to the Sun is much larger than the diameter of land, the Earth is considered as a whole.
b) Yes, it can. Over a month of the Earth covers thee distance, which is much larger than the diameter, the Earth is considered as a whole.
c) No, it can't. The diameter of a material point, by definition, is zero
d) No, it can't. To determine the speed, it is necessary to know the radius of the Earth, which is zero for the material point.
e) yes, it can. The land is considered as a whole.