The velocity of a particle moving in the xy plane is given by = (5.5 t - 4.5 t2) + 8.8, with in meters per second and t (gt; 0) in seconds. (a) What...

The velocity of a particle moving in the xy plane is given by = (5.5 t - 4.5 t2) + 8.8, with in meters per second and t (> 0) in seconds. (a) What is the acceleration when t = 4.7 s? (b) When (if ever) is the acceleration zero? (c) When (if ever) does the speed equal 10 m/s?