the bumper cars at the state fair have identical 1.0-mm-long horizontal springs protruding from the front of each car. a 250 kgkg car traveling at 1.5 m/sm/s has a head-on collision with a 150 kgkg car traveling at 2.5 m/sm/s in the opposite direction. the two springs are each compressed by 25 cmcm when the cars are instantaneously at rest, just before they rebound