A piston in an engine oscillates up and down from a rest position as shown. W I l The motion of this piston can be approximated by the function htt) = 0.05cos(13t), where t is time, in seconds, and b is the displacement of the piston head from rest position, in metres, at time t. 3) Determine an equation for the velocity of the piston head as a function of time. II) Find the maximum and minimum velocities and the times at which they occur