In Example 8.7, a 0.250 kg object moving at 2.00 m/s strikes a stationary 0.400 kg object and emerges at 45.0 degrees with a speed of 1.50 m/s. After finding the second object's velocity using momentum conservation along both axes, what does the source say about comparing the kinetic energy before and after this specific collision?

1. Momentum conservation along the x and y axes is enough to solve for the unknown final velocity and angle of the second object, regardless of whether the collision is elastic. 2. The source then goes further and compares the internal kinetic energy of the system before and after this particular collision. 3. It finds the internal kinetic energy is less after the collision, and concludes that this specific collision is inelastic. 4. This shows that solving the momentum equations alone does not tell you whether a two-dimensional collision is elastic, since that requires a separate kinetic energy check. _Source: OpenStax College Physics (CC BY 4.0), Ch 8 "Linear Momentum and Collisions", section 8.6 Collisions of Point Masses in Two Dimensions_