A student tries to raise a chain consisting of three identical links. Each link has a mass of 300 g. The three-piece chain is connected to a string and then suspended vertically, with the student holding the upper end of the string and pulling upward. Because of the student's pull, an upward force of 12 N is applied to the chain by the string.
(a) Draw a free-body diagram for each of the links in the chain and also for the entire chain considered as a single body.
(b) Use the results of part (a) and Newton's laws to find (i) the acceleration of the chain and (ii) the force exerted by the top link on the middle link.