the slider p can be moved by means of the string s, while the slotted arm rotates about point o. The angular position of the arm is given by theta=.8t-t^2/20, where theta is in radians and t in seconds. the slider is at r=1.6m when t=0 and thereafter is drawn inward at a constant rate of .2m/s. Determine magnitude and direction (expressed by the angle alpha relative to the x-axis) of the velocity and acceleration of the slider when t=4.