A238 92u nucleus is moving in the x-direction at 5.0 × 105 m/s when it decays into an alpha particle 4 2he and a 234 90th. if the alpha particle moves off at 21.2° above the x axis with a speed of 1.4 × 107 m/s, what is the recoil velocity of the thorium nucleus? assume the uranium-thorium-alpha system is isolated; you may also assume the particles are pointlike.

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.