The energy applied in friction welding is given by the formula E = IS2/C, where I is the moment of inertia of the flywheel, S is the spindle speed in rpm, and C is a constant of proportionality (5873, when the moment of inertia is given in lb-ft2). For a spindle speed of 600 rpm and an operation in which a steel tube (3.5 in. OD and 0.25 in. wall thickness) is welded to a flat frame, what is the required moment of inertia of the flywheel if all of the energy is used to heat the weld zone (approximated as a material 0.25 in. deep and directly below the tube)? Assume that 1.4 ft-lbm is required to melt the electrode?