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Does the front windshield of a car slow down

4hw.com.cn: I believe many people have a question about the front windshield of a car, that is, whether there is a visual deceleration effect. Because at high speed, it's not that fast to see things. In fact, if you've ever driven a big truck and now you're driving a car, you'll find that they have a different sense of speed. Driving a truck at over 60 per hour is almost as fast as the wind, while a car doesn't feel fast even if it's over 100, and the more advanced the car, the more obvious the feeling.

At this time, you must think that something must be added to the front windshield of the car to make it have the function of deceleration, and thus create a unique Chinese term: deceleration glass. But if you say the word to a crooked nut, he will be confused. So does car glass really slow down? Let's talk about it today.

The front windshield should be called vehicle safety glass. It is actually a kind of laminated glass, which is made of two layers of toughened glass sandwiched with a layer of PVB film. When the glass is damaged by external force, the glass fragments still stick to the film, and will not fly out to cause secondary injury to the passengers on the vehicle. High quality windscreens have good optical performance, good light transmittance, no light distortion, etc. they can reflect the shape and motion state of the scene outside very truly. The vision is very clear, just like the visual effect without glass. In addition, sandwich technology also has a certain effect of heat insulation and soft light, making people feel more comfortable.

So does this glass slow down? The answer, of course, is No. If so, there would have been a revolution in physics. No matter at home or abroad, the concept of "deceleration glass" does not exist in the formal technical data of design units or in textbooks of relevant colleges and universities. So why do we really feel that the speed is slowing down? That's because light deceives our eyes and makes us look slower.

People judge whether an object moves and how fast it moves. It's not the linear speed, but the angular speed (degrees per second). The higher the angular velocity, the faster you will feel it moving. A point moves at the same speed. If its direction of motion is exactly parallel to the eye line of sight, the angle of view is 0-DEG;, that is, the angular velocity is 0, and you can hardly feel it moving. When the direction of motion is perpendicular to the eye line of sight, the angular velocity is the largest, and you can feel the very fast movement speed. For example: when an electric bicycle passes in front of your car, you will feel its speed is very fast; if you drive in the same direction with him, you will feel that it is very slow to ride, and soon you can overtake him. This is that different angles produce different speed senses.

In addition, the size of the angular velocity is also related to the distance. The farther the distance is, the smaller the angular velocity is. The closer the distance is, the greater the angular velocity is. For example, the speed of the earth around the sun is as high as 30 km / s, which is faster than the speed of the third universe, but we can hardly feel it on the earth, because we are too far away from the sun! When we look at the airplanes in the sky, we feel that they are not fast at all. In fact, their speed is as high as 800 kilometers per hour. When we drive, the objects close to the window will flash by, but when we look at the distant mountains, we feel that the movement is very slow. The same speed on the road is different from that in the tunnel, that's why.

Different vehicle models, because of the different length of the front, the inclination of the glass, the height of the seat, etc., the driver's perspective will be different, and the angular speed of the observed object will be different, which will produce different speed sense. Trucks, buses, etc. are flat headed, the front windshield is almost vertical, the sitting posture of people is high, and the visual angle is large. The driver can see the road near the front of the car, and naturally feel the speed is very fast. Because the car has a long front, the glass slope is large, the driver's sitting posture is low and the position is back, so the line of sight is relatively flat, and the nearest distance that the driver can see is relatively long The angle is smaller, the same speed feels much slower! That's the main reason for the slowdown. It doesn't slow down the speed of light, but it creates a visual error in our eyes.

In addition, different speed sense of the car is also related to ride comfort and NVH of the car. When driving 50km / h on the road with poor pavement quality, the speed will be slightly faster; when driving 100km / h on the flat expressway, the speed will be very slow. It can be seen that the more stable the vehicle is, the slower it feels. Generally, high-end cars have better ride comfort, driving more smoothly, sound insulation and noise reduction are very good, the noise inside the car will not be very loud when driving fast and slowly, and the feeling is not so fast, which gives us a 'deceleration' feeling.

Is the glass of high-speed railway a 'deceleration glass'?

China's high-speed railway can reach a top speed of 300 kilometers per hour, but people sitting in the car don't feel so fast. Many people think that the glass of high-speed railway is also a kind of 'deceleration glass'. In fact, the principle of window glass of high-speed railway is the same as that of front windshield glass of automobile. It is a flat glass with good optical performance and explosion-proof performance, which is called vehicle safety glass. Its flatness is very high, light distortion is small, the scene will not be deformed, the vision is comfortable, not dazzling. This kind of glass can truly reflect the shape and speed of the scenery outside the car. There is no so-called deceleration effect. The reason why the passengers feel unhappy is that the subgrade of high-speed railway is generally elevated and far away from the scenery. Seeing the scenery in the distance, because of the small angular speed, gives the impression that the car is slow. In addition, the train runs very smoothly and quietly, which also gives passengers a slow feeling.

The deceleration glass, after years of misinformation from the old drivers, has become a very tall term. Many people can't explain the different sense of speed when driving different models, so they naturally believe that 'the car glass can slow down'. In fact, it just takes advantage of our visual errors and deceives our eyes. But this is a kind of good faith deception, which can let us give full play to the speed advantage of the car to the greatest extent, and promote our work efficiency.