El principio de Pascal o ¿Cómo multiplicar tu fuerza?

Can you imagine lifting a car with just the strength of your arms? Or stop a bus with a little movement of your foot? Well, this is perfectly possible and it happens every day!

but wait! Do not go running to the street to want to stop a car kicking. These wonders are possible thanks to hydraulic technology developed from the scientific genius of Blaise Pascal and have even made it possible to move buildings!

Today we are going to explain to you. . .

How to multiply your strength? Pascal's principle Today's video is sponsored by Platzi, which offers you the Soft Skills course for professional development: attitudes and habits such as leadership, communication and time management, to improve your performance. Use the link platzi.

com/softskills that you can find in the description to get a discount and stay until the end of the video to find out more! Platzi is the online platform that helps you adapt to the future. They say that back in the 17th century, the French physicist, mathematician and theologian Blaise Pascal bet that he could burst a barrel with a liter of water!

A strong barrel filled with water was connected, perfectly sealed, by a metal tube 10 meters long. Then someone, using a ladder, climbed up and poured a liter of water in, little by little, until What do you think happened? catapun!

The barrel burst! To be honest, there's no certainty that Pascal actually did this experiment, but variants have been done many times since, and it works! But why?

Pascal's principle is a physical law that belongs to hydrostatics: the branch of hydraulics that studies fluids in a state of rest and, to understand it, we need to be clear about two notions. The first is the concept of pressure. In physics, "pressure" refers to the force exerted per unit area.

That is, it is the amount of force that is applied to a given surface. Although the force is the same, the pressure increases if the area is decreased. If you maintain a constant force but decrease the area over which that force is applied, the pressure will increase.

This is because by decreasing the area, the same amount of force is being distributed over a smaller surface area. That's why it's possible to lie on a bed of nails without getting hurt, but not on a single nail. Ouch!

The second important notion is that fluids in a liquid state are considered incompressible: they do not compress. In other words, they do not change their volume when pressure is applied to them. If you take a sponge ball and squeeze it, you can make it smaller: decrease its size and increase its density.

The same goes for air and other gases: if you take a syringe filled with air, cap the outlet (no needle! ) and press the plunger, you can see how the air is compressed and when you release the plunger it returns to its original volume. Air is elastic!

What happens is that, when you squeeze the syringe, the molecules of the gases that make up the air get closer together: as the volume decreases, the density increases. But water doesn't behave like that: it can't be compressed. Well, it does compress a little bit, but so little that, for practical purposes, it's considered "incompressible.

" Try it with the syringe, now filled with water, it no longer feels elastic, it can't be compressed! The shape of their molecules causes them to fit together in a way that doesn't leave much space between them. This means that if you had a tube filled with water with two equal plungers, all the pressure applied to one end would go all the way to the entire inside surface, including the plunger at the other end.

And that is Pascal's principle: "A pressure change in a confined incompressible fluid is transmitted with equal intensity in all directions and at all points in the fluid. " In other words: the pressure will spread uniformly: the pressure at this point is equal to the pressure at this point and at this point and at this point. .

. In other words, if there were a sphere with little holes on the other side of the syringe, all the squirts would come out with the same force. Seems like common sense!

But it has staggering implications. Imagine that you have a confined fluid with two pistons or plungers at each end. We are going to call this small inlet piston and this large outlet piston.

If we press the input button, we know that the output button will move, but wait! Since the pressure is the same at all points and the output piston has more area, it means that the output piston will exert more force than was applied to the input piston! Let's say that you put a weight of 3 kilograms on the inlet piston and that the area of ​​the piston in contact with the liquid is 1 square centimeter.

The pressure then is 3 kilos per square centimeter. This pressure is transmitted throughout the liquid, to the walls of the container and to the outlet piston, whose lower surface is 5 square centimeters. Each square centimeter receives the pressure of 3 kilos: which means that the piston exerts a force of.

. . let's see: 5 times 3 is equal to 15.

. . 15 kilograms!

What witchcraft is this! ? This operation can be expressed mathematically with this equation: Force 2 is equal to force 1 multiplied by the result of dividing area 2 by area 1.

In our example: we divide 5 square centimeters by 1 square centimeter. That gives us 5. We multiply that by 3 kilos per centimeter squared and the result is 15: with only 3 kilos of input force, we could push a weight of up to 15 kilos.

But how to explain that force appears out of nowhere? Well, surely you have noticed that, although the weight we moved here is 5 times greater than the one here, the distance from here is much greater than the one here. This is because the volume of fluid that we displace on the output piston side is equal to the volume of fluid on the input piston side.

If the inlet moved 10 centimeters and its underside has an area of ​​1 square centimeter, it is easy to calculate that it displaced 10 cubic centimeters of liquid. If we put these 10 cubic centimeters on the other side, they form a cylinder whose upper face we know is 5 square centimeters, which means that its height is A see, 10 divided by 5 is… 2… 2 centimeters. Moving the inlet plunger 10 centimeters down only moved the outlet 2 centimeters up.

If you want to experience Pascal's principle in a tangible way, you can take two syringes (one thin and one thick, without needles), fill them with water, and attach them to one of those hoses used in aquariums, also filled with water. You will notice that pushing the narrow plunger moves the wide one and requires much less effort than using the thick syringe to move the thin one. In addition to the fact that the thin syringe travels a greater distance than the wide syringe.

Can you think of inventions that could make use of this? And it is that this exchange of distance for force can be very well used. When a bus driver steps on the brake pedal, he is using a hydraulic mechanism that amplifies a small force until it is capable of stopping the movement of a multi-tonne vehicle.

If you use a jack to raise your car when you have a flat tire, you are also taking advantage of Pascal's principle by multiplying the force in your arms. In addition to being used in building elevators, cranes that lift heavy loads, those hydraulic presses that crush anything, and vehicle steering systems, Pascal's principle has been used to move entire buildings! Jorge Matute Remus was a Mexican engineer who accomplished an impressive feat in the 1950s: he moved the telephone building in Guadalajara, Mexico, to avoid demolition.

To achieve this, Hooch Remus designed and built a system of rails and rollers that were placed under the building, along with 12 hydraulic jacks to move it, inch by inch, without the help of motors, and while people continued to work inside! And why did that barrel burst? This is called the hydrostatic paradox: the pressure, in this case, depends only on the height and width of the tube, not on the amount of water: even if the liquid is little, the column is concentrated in a very small area, which that increases the pressure, which, as we have already seen, exerts an equal force in all directions on the barrel.

If the tube is high enough, the barrel breaks apart! By the way: in this video we were using “kilo per square centimeter” as the unit to measure pressure, but a widely used –and more appropriate– unit is the “newton per square meter” or Pascal. Each kilo per square centimeter equals 98,066.

5 Pascals, named after its discoverer, Blaise Pascal. Curiously! To succeed professionally, not only technical knowledge is important: with Platzi, identify which attitudes, habits and ways of thinking are helping you grow and which are holding you back.

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