Consider a four-bar linkage for which ground link 1 is 14 in, input link 2 is 7 in, coupler link 3 is 10 in, and output link 4 is 8 in. The fixed x and y axes are specified as horizontal and vertical, respectively. The origin of this reference frame is coincident with the ground pivot of link 2, and the ground link is aligned with the x axis. For input angle θ2 = 60◦ (counterclockwise from the x axis):

(a) Using a suitable scale, draw the linkage in the open and crossed postures and measure the values of variables θ3 and θ4 for each posture.

(b) Use trigonometry (that is, the laws of sines and cosines)

to determine θ3 and θ4 for the open posture. (c)

Use Freudenstein’s equation to determine θ3 and

θ4 for both postures.

(d) Use the Newton-Raphson iteration procedure to determine θ3 and θ4 for the open posture. Using the measurements in

(a) as initial estimates for θ3 and θ4, iterate until the two variables converge to within 0.01◦.