Can cars really explode after a collision like in the movies?

One of the most ridiculous yet entertaining scenes in Hollywood movies is the car chase scene. Viewers love a fast and dramatic car chase, and almost all cars (except the main character's) will explode upon impact.

Components of a car explosion

To understand whether a car can explode and fly into the air upon impact, we first need to properly understand the explosion itself . All the processes that surround us in everyday life can be explained by thermodynamics, a branch of physics that studies the heat and energy changes of a system.

In thermodynamics, scientists primarily study the properties of a system, such as pressure, volume, and temperature, and we understand how these properties change as energy and work (system ability to do something).

All the processes we see around us, from the cooling of food in a refrigerator to the flow of water from a water tank, result in changes in the above quantities (and a little bit of entropy, which is the property of of the universe to prefer chaos).

Thermodynamics is the study of heat, work, and energy. The term thermodynamics (or thermodynamics) has two meanings: The science of heat and heat engines (classical thermodynamics); The science of systems in equilibrium (equilibrium thermodynamics). Initially, thermodynamics only had the first meaning. Later, the pioneering works of Ludwig Boltzmann brought about the second meaning.

From a thermodynamic perspective, an explosion is a very rapid volume expansion, accompanied by the release of a large amount of energy. For an explosion to occur, we need flammable gases. These gases must be present in a confined place where they can be subjected to very high pressures. However, as we know, for something to burn, it needs an abundant amount of oxygen. And finally, we will need a spark to ignite the flammable gas.

So… can a car explode?

Before we need to determine whether there could be a large explosion inside the car's gas tank or engine - In fact, for a car using traditional fuel to move, inside the engine There must be many small explosions from burning a mixture of gas and fuel to do work.

So if there are small explosions inside the car, could there be large explosions as well?

A conventional car engine operates according to the laws of thermodynamics and can be considered a repeating process of 4 steps, so it is called a 4-stroke engine - The shaft is moved by a piston. tones go up and down.

The Carnot cycle principle is used in automobile engines. Explosions will be made to put pressure on the piston and push the piston to move. The cycle of a car's internal combustion engine will have 4 steps to convert gasoline into vehicle operation. That's called a 4-stroke engine that includes intake, compression, combustion and exhaust.

The piston first moves down by drawing air into the cylinder (the air/fuel mixture is introduced through open valves). This pushes the piston down. When the valves close, the piston begins to rise, thereby compressing the air in the cylinder.

A small spark creates a very small explosion inside the cylinder (as explained earlier, compressed air + spark + oxygen = explosion) which pushes the piston down.

The exhaust valve then opens and the air/fuel mixture escapes, causing the piston to rise.

These four steps continue to happen in rapid succession, helping the car move forward.

Pistons in car engines.

If there is a small explosion, can there be a big one?

With everything we've just learned, there are definitely things in cars that are flammable and can even explode, so are the big explosions in movies true?

The simple answer is no.

The car contains gasoline, which is a very flammable liquid, but there are two things to note about it. Gasoline can be flammable, but not in an explosive form, nor as a gas inside the vehicle.

Gasoline is introduced into the engine in small amounts as a mixture with air, but not enough to cause a major explosion (only very small amounts are used to push the piston, as shown above). The fuel tank is made to contain fuel and does not create pressure, so the pressure in the tank is not enough to cause an explosion.

One of the favorite "spices" of American action movie producers or world action movies in general is explosion scenes, especially vehicle explosions.

Contrary to popular belief (as shown in movies), cars are not prone to explosions, and even a burning car is very difficult to explode. The necessary conditions for an explosion to occur are not met after the car encounters a major collision.

Even burning a car won't cause it to explode ; it only burns as long as there is fuel in the car. So unlike most things shown in movies, cars exploding and falling like shrapnel on the scene is not a realistic outcome!