The retractable shelf shown is supported by two identical linkageand-spring systems; only one of the systems is shown. A 20-kg machine is placed on the shelf so that half of its weight is supported by...

The retractable shelf shown is supported by two identical linkageand-spring systems; only one of the systems is shown. A 20-kg machine is placed on the shelf so that half of its weight is supported by the system shown. If the springs are removed and the system is released from rest, determine (a) the acceleration of the machine, (b) the tension in link AB. Neglect the weight of the shelf and links.