Final answer:
When parking on a hill with no curb, turn your steering wheel toward the side of the road when facing downhill, and away from the side of the road when facing uphill. Apply the parking brake in both cases. This prevents the vehicle from rolling into traffic if the brakes fail.
Step-by-step explanation:
When you park on a hill with no curb and are facing uphill or downhill, you should always set your parking brake. Additionally, steering is critical to ensure your vehicle doesn't roll into traffic if the brakes fail. If you are parked facing downhill, turn your steering wheel toward the side of the road. This way, if your vehicle starts to roll, it will go off the road rather than into traffic. Conversely, when facing uphill, turn your steering wheel away from the side of the road so that the back of the front wheels rest against the curb, which will stop the car from rolling into traffic.
In a scenario where a truck of mass 1.2 tons is parked at the top of a 150 m high hill, if the parking procedures are not correctly followed and the truck begins to roll freely down the hill, the resulting situation could be hazardous due to the potential energy transforming into kinetic energy, leading to a very fast and uncontrollable descent.