When a vehicle moves very fast, it creates a temporary phenomenon known as low pressure behind it. This low pressure is a result of the airflow around the vehicle and is commonly referred to as "drag" or "aerodynamic drag." Let's delve into the details to understand this process better.

Understanding Aerodynamic Drag:
Aerodynamic drag is the resistance experienced by a vehicle as it moves through the air. When a vehicle accelerates, the air in front of it is displaced, causing it to flow around the vehicle. As the air flows around the vehicle, it creates areas of high and low pressure.

The Bernoulli's Principle:
The low pressure behind a fast-moving vehicle can be explained by Bernoulli's principle, which states that as the speed of a fluid (in this case, air) increases, its pressure decreases. When a vehicle moves quickly, the airflow around it speeds up, resulting in a decrease in pressure.

Creating Low Pressure:
The shape of the vehicle also plays a crucial role in creating low pressure behind it. Modern vehicles are designed with streamlined shapes, such as curved bodies and sloping roofs. These shapes help in reducing air resistance and minimizing drag.

Effects of Low Pressure:
The low pressure created behind the vehicle can have a few effects:

1. Suction: The low pressure acts like a vacuum and can pull objects towards it. This suction effect can be experienced when standing close to a fast-moving vehicle, where you may feel a force pulling you towards the vehicle.

2. Turbulence: The low-pressure area can cause turbulence in the surrounding air. This can be observed through the swirling air and dust particles that may be visible behind a moving vehicle.

3. Fuel Efficiency: The low pressure helps in reducing the amount of energy required to overcome air resistance, thus improving the vehicle's fuel efficiency.

Overall, the low pressure created behind a fast-moving vehicle is a temporary phenomenon caused by the vehicle's shape and the airflow around it. Understanding aerodynamic drag and its effects is important in designing vehicles that are more fuel-efficient and have better performance.