A student tries to raise a chain consisting of three identical links. Each link has a mass of 0.360 kg. 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 13 N is applied to the chain by the string. The chain accelerates 2.2 m/s^2
Find the force exerted by the top link on the middle link.
What does this question mean? Is it asking for some sort of normal force? How do I find the answer?