While visiting the amusement park, Sarah and Sam choose to ride the bumper cars while their instructor records video of their collisions. Back in the classroom, the students analyze a head-on collision between Sarah and Sam’s two cars. The velocity of each car after the collision is equal to the velocity of the other car before the collision (i. e., the cars switch velocities). What can the students infer about the masses of the bumper cars?

Their masses are equal because both momentum and kinetic energy are conserved.
Their masses are unequal because both momentum and kinetic energy are conserved.
Their masses are unequal because neither momentum nor kinetic energy is conserved.
Their masses are unequal because neither momentum nor kinetic energy is conserved.