Question

Problem 6.41 Part A Our Sun rotates about the center of our Galaxy mc 4 x 10 "kg) at a distance of about 3 x 101 light years What is the period of the Sun's orbital motion about the center of the Galaxy? Express your answer using one significant figure. yen (3.00 × 108 m/s) . (3.16 x 10, s/yr) . (1.00 yr)] Submit My Answers Give Up

Answer 1

We use Kepler's third law, T² = 4p²r³/Gm_E, for the motion of the Sun:

   T² = 4p²r³/Gm_Galaxy;

= 4p²[(3 x 10⁴ly)(3 x 10⁸m/s)(3.16 x 10⁷s/yr)]³/(6.67 x 10^-11N.m²/kg²)(4 x 10⁴¹kg),

          which gives

                         T = 6 x 10¹⁵s =  2 x 10⁸yr. (ans)