Final answer:
When a truck descends a hill and applies its brakes continuously, the brakes can overheat due to the conversion of gravitational potential energy to internal energy. This overheating reduces the braking effectiveness, making the brakes less efficient.
Step-by-step explanation:
Loss of braking effectiveness caused by over-heating of the brakes after long, continuous, hard braking is a physics concept. When a truck descends a hill and applies its brakes continuously, the brakes must do work to convert the gravitational potential energy of the truck to internal energy of the brakes. This conversion raises the temperature of the brake material, leading to overheating. The increased temperature reduces the effectiveness of the brakes, making them less efficient in stopping the vehicle.