1) A single gas molecule of inertia m is trapped in a box and travels back and forth with constant speed v between opposite walls A and B a distance l apart. At each collision with a wall, the molecule reverses direction without changing speed.
What is the final kinetic energy of the two-car system?
Express your answer with the appropriate units.2) A physics student driving a 1300-kg car runs into the rear of a 2000-kg car stopped at a red light. From the fact that the joined vehicles skidded forward 4.0 m, the investigating police officer calculates that the speed after the collision was 7.6 m/s .
Based on this information, calculate the student's speed before impact.
Express your answer with the appropriate units.