1. The problem statement, all variables and given/known data Block A is moving to the right at 2 m/s when it collides with an identical block B that is initially at rest. After the collision, block A is moving back to the left at 1 m/s and block B is moving to the right at 3 m/s. Which answer best describes the type of collision that occurred? a) elastic b) inelastic c) perfectly inelastic d) The answer to this question depends on the precise masses of the two blocks. e) This question cannot be answered with the given information. 2. Relevant equations (m1)(v1i) = (m1)(v1f) + (m2)(v2f) KE = (1/2)mv^2 3. The attempt at a solution my teacher said the answer was a, but i thought that the answer would be e, because the initial KE of the system is 2m, while the final KE is 5m. this means an increase in KE but i dont know if increase in KE can still be considered elastic.