Two blocks are connected by a wire that has a mass per unit length of 8.50 x 10-4 kg/m. One block has a mass of 19.0 kilogram, and the other has a mass of 42.0 kilogram. These blocks are being pulled across a horizontal frictionless floor by a horizontal force P that is applied to the less massive block. A transverse wave travels on the wire between the blocks with a speed of 532 m/s (relative to the wire). The mass of the wire is negligible compared to the mass of the blocks. Find what is the magnitude of horizontal force?