Over a time interval of 1.80 years, the velocity of a planet orbiting a distant star reverses direction, changing from +20.0 km/s to -20.1 km/s. Find (a) the total change in the planet's velocity (in m/s) and (b) its average acceleration (in m/s2) during this interval. Include the correct algebraic sign with your answers to convey the directions of the velocity and the acceleration. (a) Number -4.01 Units m/s (b) Number -0.000000706 Units m/s^2