6. (a) Suppose the earth is revolving round the sun in a circular orbit of radius one b astronomical unit (1.5% 10 km). Find the mass of the sun. G = 6.67 x 10" N m² kg 2. (b) If the mass of sun is 2 x 10" kg, distance of earth from the sun is 1.5 x 10¹ m and period of revolution of the former around the latter is 365.3 days, find the value of G.