Can you hold on to a high-speed car, train or plane with your bare hands?

In movies and TV series, we often see scenes like this: a person grabs onto a high-speed car, train, or even an airplane with his bare hands. Is this just a film or TV creation, or is it true? Can a high-speed car, train, or airplane really be grabbed with bare hands?

In fact, it is not difficult to verify the truth of this matter, because this is a simple problem of "force confrontation" in physics. It takes a certain amount of strength to steal a car with bare hands, because there is always a force pushing you back in the process. Only when your strength overcomes the force pushing you back can you stably steal from the car. So where does this force pushing you back come from? It comes from the wind, that is, wind pressure. So how strong is the wind pressure when the car is driving? To know the wind pressure, you must first know the wind speed.

The faster the car moves forward, the faster the wind speed on the car surface will be. Generally speaking, the speed of a car traveling on a national highway will not exceed 80 kilometers per hour, which is about 22m/s.

Knowing the wind speed, we can calculate the wind pressure. Wind pressure = wind speed squared/1600. The square of wind speed is 484, which is equal to 0.3 kN/m2 when divided by 1600, which is equivalent to 30 kg/m2. Now that we know the wind pressure, we also need to know the force-bearing area of ​​the human body. If a car is driving at high speed, and we hold the car window with both hands, then our body must be in a horizontal posture with the head facing forward and the feet facing backward, so our force-bearing area is the cross-section of our body. So how big is the cross-sectional area of ​​the human body? This may be quite different for different people, so let's take 0.1 square meters.

With the wind pressure and the force-bearing area, we only need to multiply the wind pressure by the force-bearing area to get the wind thrust exerted on the human body.

List the formula, 30X0.1=3, so the wind thrust on the human body when clinging to the outside of a moving car is about 3 kg. So can the human grip strength resist the 3 kg thrust? Of course there is no problem. Even the most physically challenged adult women have a grip strength of no less than 18 kg. So anyone can cling to a moving car with bare hands. As long as you are not afraid, you will not fall off. Therefore, the scenes of clinging to cars with bare hands in film and television works are realistic. Clinging to cars with bare hands is no problem, so can clinging to trains with bare hands? Let's first see how fast the train is.

For ordinary trains, the maximum speed is about 120 kilometers per hour, but the actual speed of most trains cannot reach this speed.

It doesn't matter, let's calculate at the maximum driving speed. 120 kilometers per hour, which is 33 meters per second, squared is 1089, wind pressure is equal to the square of wind speed divided by 1600, that is, 1089 divided by 1600, the result is 0.68 kN/square meter, which is 68 kg/square meter. The cross-sectional area of ​​the human body is still 0.1 square meters, 68X0.1=6.8, so the thrust of the wind on the human body when clinging on a train is 6.8 kilograms. We have said before that the grip strength of the worst adult female will not be less than 18 kilograms, so clinging on a train is also something that everyone can do. Cars and trains are both ground-based transportation. If it is an airplane flying in the sky, can it be grabbed by hand?

Although airplanes fly in the sky, the calculation method is no different from that of cars and trains. First of all, we need to know the flying speed of the airplane.

The cruising speed of Boeing series passenger aircraft is about 900 kilometers per hour, which is incomparable to cars and trains. 900 kilometers per hour is equivalent to 250 meters per second, and squared, it is equal to 62500. Wind pressure is equal to the square of wind speed divided by 1600, that is, 62500 divided by 1600, the result is 39.1 kilonewtons/square meter, which is 3910 kilograms/square meter. The cross-sectional area of ​​the human body is still taken as 0.1 square meters, 3910X0.1=391, so the thrust of the wind on the human body when clinging to the plane is 391 kilograms. Obviously, not everyone can cling to the plane with bare hands, so is there anyone who can cling to the plane with bare hands?

According to the data, the strongest adult male's grip strength can reach up to 58 kg, but 58 kg is still far from the thrust of 391 kg, so it is an impossible task to hold on to a Boeing passenger plane with bare hands.

So how are the shots of grabbing the plane with bare hands in film and television works produced? There should be two possibilities for the presentation of these shots. One is the special effects presented through post-production, and the other possibility is to let the plane fly at a very low speed to reduce the wind speed, thereby reducing the wind pressure and reducing the thrust on the human body. However, this is very expensive. It not only requires the cooperation of a large number of crew members, but also requires an experienced pilot. For an airplane, maintaining high-speed flight is not a problem. Low-speed flight is the most difficult, because the lift of the airplane comes from the pressure difference between the upper and lower surfaces of the wing. The slower the flight speed, the slower the airflow speed, the smaller the pressure difference, and the smaller the lift. Unless the movie has a wealthy investor, it should not be shot like this.

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