A block of mass 1.20 kg is placed on a frictionless floor and initially pushed northward, whereupon it begins sliding with a constant speed of 3.91 m/s. It eventually collides with a second, stationary block, of mass 4.33 kg, head-on, and rebounds back to the south. The collision is 100% elastic. What will be the speeds of the 1.20-kg and 4.33-kg blocks, respectively, after this collision?
2.21 m/s and 1.70 m/s
1.70 m/s and 2.21 m/s
1.88 m/s and 1.96 m/s
1.77 m/s and 2.09 m/s