A polo ball is hit with a mallet off the edge of a cliff. Its x- and y-coordinates as functions of time are given by x = 18.2t and y = 3.60t-4.90t2, where x and y are in meters and t is in seconds. (Do not include units in your answer.) (a) Write a vector expression for the ball's position as a function of time (in m), using the unit vectors i and j. (Give the answer in terms of t.) m By taking derivatives, do the following. (b) Obtain the expression for the velocity vector vas a function of time (in m/s). (Give the answers in terms of t.) m/s (c) Obtain the expression for the acceleration vector a as a function of time (in m/s). m/s (d) Next, use unit-vector notation to write expressions for the position, the velocity, and the acceleration of the polo ball at t=2.76 s. (Assume the position is in m, the velocity is in m/s and the acceleration is in m/s.) x m/s m/s