Final answer:
The statement is true; heavier vehicles or those moving faster require the brakes to absorb more heat to stop, as the brakes must convert more kinetic and potential energy into heat energy to reduce the vehicle's speed.
Step-by-step explanation:
The statement that the heavier a vehicle or the faster it is moving, the more heat the brakes have to absorb to stop is true. When a vehicle like a truck applies brakes, especially on a downhill run, the work done by the brakes converts the gravitational potential energy into increased internal energy, which manifests as higher temperatures in the brake material. This process helps to reduce the vehicle's speed by converting potential and kinetic energy into heat.
For a heavier vehicle, or when a vehicle is moving faster, more energy is involved due to either greater mass or higher velocity. The brakes have to dissipate this energy, which means they will have to absorb more heat. This is further evidenced by the fact that truck brakes can overheat on long downhill runs due to the rapid temperature increase from the energy conversion, showing that a larger amount of potential energy (from a heavier truck or higher speed) results in a higher increase in brake temperature, possibly to the point of overheating if heat dissipation to the environment is not fast enough.