Why do many car front windows have slanted windows? What are the little black dots on the windows used for?

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Cars have entered thousands of households

From daily travel to short-distance travel, it is indispensable

Greatly facilitated our lives

Modern cars are developing very fast, and cutting-edge technologies and innovative achievements in the fields of electrification, hydrogen energy, future mobility, mass-produced cars, etc. are undergoing dizzying changes. But have you noticed that no matter how the car changes, the upper part of the front window glass is always tilted backward at a certain angle when it is installed. Why is this?

Today we will study:

Why does the front window tilt backwards?

Why do many drivers only open one side of their car windows?

What other little-known facts about car windows?

Car front window

1. Beautiful appearance

Tilting the car's front window glass backwards at a certain angle can make the vehicle look more beautiful without any abrupt edges or corners.

2. Reduce air resistance

When a car moves forward, it will encounter strong air resistance, and the tilted front window glass can make the oncoming air flow easily over the glass. Therefore, the tilted installation of the front window glass conforms to the principle of reducing air resistance .

Of course, there are exceptions, such as the front windshield of a large truck. Although the space of a car is small, it has comprehensive facilities in all aspects, and the seats can be put down for people to lie on their backs to rest, but this is impossible for a large truck. Trucks travel on the road for much longer transportation time than cars, so in order to improve the driver's driving comfort, the cab can only be designed as wide as possible, and the space left by vertical glass is larger than that of inclined glass.

3. Ensure driving safety

The more important reason for installing the car's front window glass at an angle is to ensure driving safety.

When you are on a bus at night and look out through the vertical side windows, if the interior of the bus is bright, the scenery inside the bus will form a clear virtual image on the glass, which will overlap with the scenery outside the window, giving people the illusion that it is difficult to distinguish between inside and outside. At this time, the glass window is like a transparent mirror.

If the front windshield of the car is also installed vertically, the virtual image of the scene inside the car will be reflected on the front windshield, overlapping and mixing with the image of the scene outside the car, causing visual confusion for the driver who is observing the road, traffic and pedestrians, which can easily lead to traffic accidents. So try not to turn on the lights inside the car when driving at night .

So, why can we avoid visual interference by tilting the front windshield at a certain angle? This is because the scenery in front of the car is seen by the driver through the light passing through the glass, while the virtual image of the scenery inside the car is seen by the driver based on the principle of light reflection from the glass .

Therefore, after the car windshield is tilted, its light transmission performance will hardly change. According to the imaging principle of a plane mirror, the size of the image formed by the plane mirror is equal to the size of the object, the distances between the image and the object from the plane mirror are equal, and the line connecting the image and the object is perpendicular to the mirror surface, that is, the image formed by the plane mirror and the object are symmetrical about the mirror surface. Therefore , when the car windshield is tilted forward, the virtual image of the scenery inside the car is reflected above the driver's field of vision, which plays a very practical role in driving safety .

Car window open on one side

If you drive without opening the windows, the carbon monoxide concentration in the car will increase, and you will feel sleepy and need fresh air to "wake up." When driving on ordinary roads, opening the windows can increase comfort, but it is not suitable in all situations, and there are also some rules for how to open the windows.

1. Open a slit on one side to disperse odor

If the front window on one side is opened a little, the air inside the car will squeeze the smoke or other odors out of the car. But if the window is opened wider, the strong force of the airflow outside the car will squeeze the smoke into the car and flow out from the rear exhaust port.

When a passenger smokes, open the window on the smoker's side so that the secondhand smoke can be expelled quickly.

2. Open two windows diagonally to reduce noise

When you open two windows facing each other while driving, the noise will be very loud, and you will hear a "whooshing" sound all the time, and you may not even be able to hear what people are saying.

At this time, opening a front window and a diagonal rear window can not only allow air to flow freely, but also be very helpful for cooling and ventilation. Moreover, this ventilation makes little noise, which is suitable for taking children out and letting them sleep quietly.

3. Open three fans and close one fan for quick ventilation

It is best to open two front windows and one rear window. This will create a high-pressure area in the rear row. The wind will be softer, making it easier for people to accept. It can also prevent debris from outside the car from entering, making it safer.

Car window tips

1. What are the small black spots on the car windows used for?

People who often take the bus may notice a small detail: there is a circle of small black dots on the edge of the car window. Many people think that this is a sticker from the manufacturer, but in fact these small black dots have real scientific uses.

Our car windows are fixed to the car with glue. When the car windows are exposed to the sun in the hot summer, the metal frame around the car windows will heat up and expand, which may cause the car windows to explode. In winter, the temperature is low and the car is hot, resulting in a large contrast between the surrounding frame and the middle, which may also cause the car windows to explode. The small black spots on the car windows can protect the car windows and reduce damage to the windows from the outside.

These small black spots, which gradually become smaller from the window frame to the middle, serve as a transition, dispersing the thermal expansion , reducing the pressure on the car window and reducing the risk of explosion.

2. What are the wonderful uses of car sunroof?

• In traffic jams: exhaust gas

Everyone must have experienced traffic jams, where a large number of vehicles are stuck together and the exhaust gas is quite large. If the side windows are open, the surrounding exhaust gas can easily enter the car. At this time, you can close the side windows and open the sunroof. Because the sunroof ventilation uses the negative pressure principle , negative pressure ventilation will exhaust the exhaust gas in the car, and the dirty air will not enter the car.

• While driving: reduce noise

When driving on the highway, turning on the heater for too long will increase the driver's fatigue, but opening the side windows will produce a lot of wind noise. When the vehicle speed reaches 100 kilometers, the noise can be as high as 110 decibels, while opening the sunroof is only 69 decibels, because the sunroof adopts an aerodynamic design , which can reduce wind noise when opened.

3. Opening four windows at the same time has low ventilation efficiency

Some people think that opening all four windows will improve ventilation. In fact, the ventilation efficiency is low and the airflow direction in the car is chaotic during driving.

When the airflow around the car window reaches its peak, the large amount of air accumulated in the car can easily interact with each other to produce turbulence, which can even blow up the light ornaments in the car in extreme cases. If some buttons in the car are not installed firmly, they may also be blown off, which is very dangerous.