Final answer:
The question involves physics concepts such as forces in equilibrium, inertia, and Bernoulli's principle. Faster speeds than necessary over the top of a crest can cause a car to lose contact with the road, while slower speeds will maintain contact. Overtaking a truck can result in decreased air pressure and potentially hazardous road conditions.
Step-by-step explanation:
The question appears to discuss the effects of speed and gravity on a car travelling on a pavement, particularly when overtaking at a high speed or going over the top of a slope. It involves concepts related to Newton's laws of motion, forces in equilibrium, inertia, and energy conservation.
Considering the scenario where a car goes over the top of a crest or hill on a road, if it goes at a faster speed than necessary to maintain contact with the road, the car may briefly become airborne. This is because the centripetal force required to keep the car on its path is not enough to compete with the inertia of the car moving in a straight line at high speed, due to which the car's tires lose contact with the road. On the other hand, if the car goes over the top at a slower than needed speed, it will remain in contact with the road, as the gravitational force and required centripetal force will be in balance, allowing for safer passage over the crest.
Moreover, factors such as air resistance and friction also play a role when overtaking as mentioned in the scenarios with the air passing between a car and a truck on a highway. When overtaking another vehicle like a truck, the car experiences reduced air pressure as it passes close to the truck due to increased air speed between the two vehicles, which could draw the vehicles closer together, a phenomenon explained by Bernoulli's principle. This can be dangerous if not properly anticipated by the driver.