Whether it be a jack or a screwdriver, they are essentially a force transfer system, which is not used in a very efficient way. And the least energy-saving jack should be the hydraulic jack. For hydraulic jacks, you should have used them, or at least have seen them. Such a jack seems to be overwhelming, as if it lifts anything heavy。
Hydraulic jacks (photo source: https://www. Indiamart. Com/)
As can be seen from the theory of the jack above, the hydraulic jack is actually a hydraulic system. And then i'm going to give you a brief introduction to the theory of hydraulic weight lifting -- the pascal principle。
The pascal principle simply states that the pressure is applied on a piston in a hydraulic system, and the increase in the piston's surface pressure is bound to produce the same pressure increment on another piston, expressed in formulas:
(f for surface pressure of the piston, and a for area of the piston)。
With pascal, we can easily understand the work of hydraulic jacks。
Hydraulic jack working principles (photo source: http://www. Lhqzby. Com/)
The above figure is a working diagram of the normal hydraulic jack, which looks complicated. The simplified rationale is as follows:
Asymmetric u-type matrix
Simply put, the hydraulic jack is actually an asymmetric u-type tube. We can understand the reason for the "heavy lifting" of the hydraulic jack based on high school physics。
As shown in the figure above, when this u tube is filled with liquid, the liquid surface on both sides should be flat, because the atmospheric pressure on both sides is equal. At this point, if pressure is applied on the left tube, the pressure of the tube increases and the water surface on the right rises to a certain height, so that the pressure on both sides is equal again, and this has nothing to do with the thinness of the pipe on both sides。
However, saving jacks may not be time-consuming, as the fall in pistons is inversely proportional to the rise in the height of the pistons and the size of the two pistons — the smaller the area of the pistons, the greater the heights that need to rise or fall. Thus, the large size ratio of the jack also means an increase in the number of pistons under pressure。
In everyday life, whether you use one of the types of jacks above to raise weight, you may feel a lot less energy, but it's only half right. It means that, while using them is much less powerful than not, the total energy you consume remains the same. For a hydraulic jack, a piston is really a little bit more energy-efficient, but to lift the weight, we need to press it many times, so the total energy required for the output has not changed, and the energy has remained constant both front and back。
In addition, life-saving devices, including jacks, wheel slides, tilts, levers, etc., are less effective. Their use does not give you additional strength, in part by adopting a strategy of “separation and governance”, which enables you to succeed in doing what seems impossible to lift。
