Final answer:
Old brake shoes returned for new friction material are referred to as cores. They are examples of recycling in the automotive industry and are involved in the transfer of kinetic energy to heat during braking.
Step-by-step explanation:
The old brake shoes that are returned to the manufacturer when new friction material is installed are usually called cores. The friction between the brake shoes and the brake drum or rotor converts the kinetic energy of the car into heat, similar to how a book sliding across a floor heats up due to friction with the floor.
With cars, the kinetic energy also encounters air resistance which creates eddies, and friction in the axle/bearings along with the constant deformation of the tire. These phenomena are all related to the transfer of energy in the context of physical motion, and the use of cores in brake shoe replacement is an example of recycling automotive parts.