(a) If we ignore the influence of other celestial objects, the Earth-Sun system is isolated, and so it must rotate about the system's center of mass. Using the data in Table 13.1, determine how far from the center of the Sun the center of mass of the system is and what fraction of the Sun's radius this distance is.

(b) As it passes the point shown in Figure 13.10b, does the comet speed up, slow down, or travel at constant speed? If the trajectory shown is part of an ellipse, where is the comet's velocity greatest? Where is it smallest?

Transcribed Image Text:

Figure 13.10 Whether an orbit is circular or elliptical, the gravita- tional force on the orbiting body points toward the Sun. If the orbit is elliptical, the Sun is at one focus, not at the center of the ellipse. (a) Orbits of Earth and hypothetical comet (not to scale) Earth in nearly circular orbit V Sun x comet in elliptical orbit