Final answer:
The factors that determine the selection of a "safe" speed when going down a long, steep downgrade include the gradient of the slope, the condition of the road, the mass of the vehicle, and the driver's skill level and experience.
Step-by-step explanation:
The factors that determine the selection of a "safe" speed when going down a long, steep downgrade include the gradient of the slope, the condition of the road, the mass of the vehicle, and the driver's skill level and experience. Let's break it down:
- Gradient of the slope: The steeper the slope, the higher the speed at which a vehicle can safely descend. In general, a gentle slope requires a lower speed for safety, while a steeper slope allows for a higher speed.
- Condition of the road: A smooth and well-maintained road provides better traction, allowing for a higher safe speed. On the other hand, a rough or slippery road surface requires a lower speed to ensure stability and control.
- Mass of the vehicle: The mass of the vehicle affects its braking distance and ability to maintain control. Heavier vehicles require a longer braking distance and may have reduced maneuverability, necessitating a lower safe speed.
- Driver's skill level and experience: A skilled and experienced driver can assess the conditions and adjust their speed accordingly. They can anticipate hazards, brake effectively, and maintain control of the vehicle at higher speeds.
By considering these factors, drivers can select a safe speed that allows for a controlled descent down a long, steep downgrade.