51. A nucleus, initially at rest, decays radioactively. In the process, it emits an electron horizontally to the east, with momentum 9.0 x 102 kg m/s and a neutrino horizontally to the south, with momentum 4.8 x 10 kgm/s. (a) In what direction does the residual nucleus move? [3] (b) What is the magnitude of its momentum? [3] (c) If the mass of the residual nucleus is 3.6 x 10-2 kg, what is its recoil velocity? [2]