If a comet has a perihelion of 1.4 AU and an aphelion of 8.5 AU, what is the semi‑major axis of the comet's orbit? What is the Axis and the period of the comet's orbit around the sun?

Light traveling in water, nwater = 1.33, strikes a plastic block at an angle of incidence of 51.4°; part of the beam is reflected and part is refracted. if the index of refraction of the plastic is 2.0, what is the angle made by the reflected and refracted beams?