4. An object's position is described by the following polynomial for Os to 10 s. S (t) = t3 - 15 t2 + 54 t where S in meters, t is in seconds. Determine: a) The object's Velocity Function; b) The object's acceleration Function; c) The object's position at, t = 4s; d) The object's velocity at, t = 4s; e) The object's acceleration at t = 4s; f) The time and velocity when object returns to its original position; g) The time and velocity when acceleration is zero. h) is the object's speed is increasing, decreasing, either if time is 4 s