Consider the four-bar chain in the figure. The angular velocity and the angular acceleration of the rotating bar AB are omega [rad/s] and alpha [rad/s2], respectively, in the directions shown in the figure. (A negative value indicates the vector is in the opposite direction to that shown in the sketch.) Calculate the angular accelerations of the bars BC and CD in the direction of the k unit vector.

(A) The angular acceleration of BC (in rad/s2)?

(B) The angular acceleration of CD (in rad/s2)?

Note : The length L is not specified. If you set up your equations correctly, you should find that L cancels out. First find the angular velocities for the bars BC and CD. You already know how to do this from an earlier question. Then you need to write the acceleration at C in two ways: First from B to C; and then from D to C. The two accelerations (both referring to the acceleration of the point C) should be equal. This vector equality gives you two equations and two unknowns.

omega[rad/s] = 18;

alpha[rad/s2] = 48;

http://micko.dyndns.org/4bar_acc.jpg