6/78 The robotic device consists of the stationary pedestal OA, arm AB pivoted at A, and arm BC pivoted at B. Mem- ber AB is rotating about joint A with a counterclockwise angular velocity of 2 rad/s, and this rate is increasing at 4 rad/s². Determine the moment MB exerted by arm AB on arm BC if joint B is held in a locked condition. The mass of arm BC is 4 kg, and the arm may be treated as a uniform slender rod. 700 mm A B 350 mm (૬૧, C . 45° 90° PROBLEM 6/78