1. The problem statement, all variables and given/known data Mars travels around the Sun in 1.88 (Earth) years, in an approximately circular orbit with a radius of 2.28 x 10^8 km Determine a) the orbital speed of Mars (relative to the Sun) b) the mass of the Sun 2. Relevant equations acceleration centripetal = 4(pi^2)(r) / (T^2) universal attraction = (G)(m1)(m2) / (radius)^2 3. The attempt at a solution Given: T = 1.88 years = 59287680s = 5.9x10^7s r = 2.28 x 10^8km = 2.28 x 10^11m Orbital speed means centripetal acceleration yes? Then, acceleration centripetal = 4(pi^2)(r) / (T^2) acceleration centripetal = 4(9.869604401)(2.28x10^11m) / (34.81x10^14s) acceleration centripetal = 90.01x10^11m / 34.81x10^14s acceleration centripetal = 2.59x10^-3m/s = 0.00259m/s How come its so slow?