Kepler's 3rd Law is expressed as T2 = k R3 where k is a constant of proportionality. ) Determine the dimension of the constant k in terms of L, T or M, inKeplers 3rd Law from this expression and show your working. Derive an equation for the orbital velocity of a planet and use your equation to show that the orbital radius is proportional to the square of the orbital velocity. The orbital period of two planets are recorded asfollows, Planet A: 12.1 days, Planet B: 23.0 davs. Calculate the ratio of the orbital radius of Planet A to planet B.