Final answer:
The correct approach when facing a downgrade is to use a lower gear to slow the vehicle down, as this allows for engine braking and better control of the vehicle. This method helps prevent brake overheating and loss of vehicle control.
Step-by-step explanation:
When approaching a downgrade, the safe and correct approach is D) Use a lower gear to slow your vehicle down. This technique allows engine braking to occur, which helps to manage speed without overheating the brakes. This is critical for maintaining control, especially on steep or lengthy descents. And, calculating the maximum deceleration of a car on a slope involves understanding the forces acting on the car, such as gravity, friction, and the normal force, which are all encompassed within the realm of physics.
For instance, in a scenario where a car experiences non-negligible friction, coasts down a hill, crests a small hill, and coasts downhill again to a stop at a gas station, the car transitions through various forms of energy. Initially, the car has potential energy at the top of the hill which converts to kinetic energy as it descends. Frictional forces and air resistance convert some of this kinetic energy into heat, slowing the car without the use of brakes. If the descent is steep enough or long enough, using a lower gear is indeed essential to avoid over-reliance on brakes and maintain control.