Final answer:
When one part of a dual air brake system in a truck is low on pressure, either the front or rear brakes will not be fully functional, leading to reduced braking efficiency and potential safety issues.
Step-by-step explanation:
If your truck has a dual air brake system and one of the systems is low on pressure, the correct answer is that c. Either the front or rear brakes will not be fully functional. This is because the dual system is designed to operate two sets of brakes independently; one typically controls the front axle and the other controls the rear. If one system has low pressure, it means that the set of brakes it controls might not engage properly, reducing the overall braking efficiency of the truck. It is important to maintain proper air pressure in both systems for safe operation.
Truck brakes are crucial for controlling the speed of the truck, especially on downhill runs where they convert gravitational potential energy into increased internal energy, thus increasing the temperature of the brake material. The mass of the truck is large compared to the brake material's capacity to absorb energy, leading to potential overheating if the system is not functioning properly.