PHYSICS · Single correct · AP · Physics 1: Algebra-based · Linear Momentum · Linear Momentum
Problem
During an experiment, students monitor the total kinetic energy of an isolated two-object system. The graph shows three constant regions:
• Region I (before t=0.40s): 9.0J
• Region II (0.40s<t<0.80s): 9.0J
• Region III (after t=0.80s): 5.0J
Two collisions occur, one at t=0.40s and another at t=0.80s. Which statement correctly classifies the collisions?
(a) Both collisions are inelastic because the total kinetic energy at the end of the experiment is lower than at the start.
(b) The first collision is elastic and the second is inelastic because the total kinetic energy decreases only after the second collision.
(c) Both collisions are elastic because kinetic energy is conserved in Regions I and II.
(d) The first collision is elastic and the second collision is perfectly inelastic because the decrease in kinetic energy indicates the objects stuck together in the second collision.