Summary of Hidrostática -Presión hidrostática-Principio de Pascal ( Semana 9-Pre San Marcos)

00:00:00 - 00:25:00

In this YouTube video about hydrostatics, the host introduces the concepts of density and hydrostatic pressure. Density is defined as the mass of a substance divided by its volume, while hydrostatic pressure is the force exerted by a liquid on a surface. The host explains the formula to calculate hydrostatic pressure and mentions the importance of considering atmospheric pressure when calculating total pressure. They also discuss vasos comunicantes and Pascal's principle, which states that any change in pressure in an incompressible fluid is transmitted equally to all points of the fluid. Finally, the video explains how Pascal's principle is applied in a hydraulic press to multiply forces.

• 00:00:00 In this section, the video introduces the concept of hydrostatics, which is the study of liquids at rest. The host explains that the term "hydro" refers to water but can also be generalized to other liquids. He then discusses two key concepts that need to be understood: density and hydrostatic pressure. Density is defined as the mass of a substance divided by its volume, and the units can be in kilograms per cubic meter or grams per cubic centimeter. The video also provides conversion factors for converting between the two units. The host explains that the density of water is commonly given as 1000 kilograms per cubic meter, while the density of oil is typically around 800 kilograms per cubic meter. Understanding these concepts is crucial for solving problems in hydrostatics.
• 00:05:00 In this section, the concept of hydrostatic pressure is introduced. Hydrostatic pressure is defined as the force exerted by a liquid on a surface. Specifically, it is the force normal to the surface divided by the area of the surface. The force normal is the component of force perpendicular to the surface, while the tangential force is the component parallel to the surface. The reason why the normal force is used to calculate pressure is because it is the force that "squashes" or compresses the surface. The units for pressure are Newton per square meter, also known as Pascal (Pa). It is important to note that hydrostatic pressure is applicable to liquids in a state of rest. Lastly, examples of hydrostatic pressure are given, such as the pressure exerted by water in a swimming pool or on a scuba diver underwater.
• 00:10:00 In this section, the speaker discusses the concept of hydrostatic pressure in a liquid. They explain that any object immersed in a liquid experiences pressure, which depends on the depth of the object. The formula to calculate hydrostatic pressure includes the density of the liquid, the acceleration due to gravity, and the depth of the object. The speaker also mentions that when there are multiple liquids in a container, the hydrostatic pressures of each liquid should be added together. Additionally, they explain the concept of total pressure or absolute pressure, which includes both the hydrostatic pressure of the liquid and the atmospheric pressure exerted by the air. The speaker emphasizes the importance of considering atmospheric pressure and reminds the viewers to add it to the hydrostatic pressure when calculating total pressure. They mention that the atmospheric pressure at sea level is 10^5 Pascal and should be added to the hydrostatic pressure in calculations.
• 00:15:00 In this section, the professor introduces the concept of vasos comunicantes, which are communicating vessels. These vessels consist of tube-shaped structures connected by the same liquid, and the pressure at different points within them is equal. To solve problems involving vasos comunicantes, one must identify two points at the same level that are connected by the same liquid, and their total pressures will be equal. The professor also explains Pascal's principle, which states that any change in pressure in an incompressible fluid is transmitted equally to all points of the fluid. This principle applies to all liquids and certain confined gases.
• 00:20:00 In this section, the principle of Pascal is explained using the example of a container filled with an incompressible fluid. Two points are identified in the fluid, with different hydrostatic pressures, and a small force is applied to a lid on top of the container, causing a change in pressure underneath it. According to Pascal's principle, this change in pressure is transmitted with equal intensity to all points of the fluid. This principle is then applied to explain the concept of a hydraulic press, which is used to multiply forces. The press consists of two pistons, with one having a smaller area than the other. When a force is applied to the smaller piston, it causes a change in pressure that results in a larger force being exerted by the larger piston. This allows for the lifting of heavy objects with a smaller force.
• 00:25:00 In this section, the speaker discusses the principle of Pascal in hydraulics, which states that the ratio of force to area is the same for two connected pistons. They provide a simple formula and an equivalent one that uses the radii of circular pistons. The speaker emphasizes the importance of understanding this principle and mentions that in the next video, they will discuss the Archimedes principle and surface tension. They conclude by bidding farewell and sending blessings to the viewers.