To demonstrate springs in a two-dimensional lattice, you build the apparatus shown below that is composed of 8 parallel chains of springs, with each chain containing 2 indentical low-mass springs in series. At the top and bottom, the springs are attached to a lightweight rod. A mass of 7kg is attached to the bottom rod. Relaxed, the distance d from the bottom to the top of the apparatus is 0.12 m. (The top of the apparatus is attached to the ceiling in the lab which is not shown.) Each of the 16 springs has a stiffness of 36 N/m. If you support the bottom of the apparatus at rest and if d = 0.344 m, what is the magnitude of the force by your hand on the apparatus?
