Notes, summaries, assignments, exams, and problems for Physics

Pressure and Fluids

What is Pressure?

Sometimes the effect of force also depends on the size of the surface on which it operates. The pressure takes into account two variables: the strength and the surface. Pressure occurs when a force acts on a unit area.

Pressure is defined as the force acting on a unit area (p = F / S). The SI unit is the newton per square meter (N/m²), which is called the pascal and whose symbol is Pa (1 Pa = 1N / 1 m²). Pressure is a scalar because it acts with an equal numerical value in all directions.

What are Fluids?

The term fluid includes both liquids and gases, and their properties are:

1. They do not have their own shape.
2. They take the form of the container that contains them.

This is because the particles that make up the... Continue reading "Understanding Fluid Pressure and Hydrostatics" »

Types of Support and Channels

Wireless support's atmosphere is leading to it being transmitted through electromagnetic waves and sound. Wired support uses some sort of cable, such as coaxial cable or fiber optics.

Channels

Channels are real-time media communication that allows the same instant. Time media are those media differed in the signal sent by the sender is stored in any information recording system, such as magnetic tapes, CDs, and DVDs.

Codes

Communication codes are legion: the languages of mankind, color codes, writing, and language.

Parameters

• Amplitude: The maximum variation of the signal about the value zero.
• Period: The time lag between two consecutive steps by maximum wave value.
• Frequency: The number of oscillations that occur during

Acoustics and Noise Principles

1. What is sound, from a technical perspective?

Answer: Sound is a mechanical vibration of a physical medium. It is a longitudinal wave that travels through the air.

2. When addressing a noise problem, what measures can be taken? Explain clearly.

Answer: Isolate the source with a solid, low-density material.

3. My neighbor's stereo is at 40 dB:

Answer: Chilean law considers a maximum of 45 dB between 9 PM (21:00 hrs) and 7 AM (07:00 hrs). Therefore, a personal solution would involve covering my ears or isolating my room.

4. A sound pressure measured in atmospheres is 2 atm. Calculate the noise intensity and discuss the obtained value.

5. Name three standards that can be referenced to solve a neighborhood noise problem:

Fundamental Concepts in Fluid Mechanics

Pressure and Phase Changes

• Evaporation: The constant movement of molecules on the surface of a liquid, allowing them to escape into the atmosphere.
• Boiling: Occurs when the pressure to which a liquid is subjected equals its vapor pressure.
• Vapor Pressure: The partial pressure exerted by molecules in the gaseous state within a container when occupying a space above a liquid.
• Saturation Pressure: The state where there is a dynamic balance between the number of molecules that evaporate and condense.
• Cavitation: A phenomenon where, if the local pressure (p) in a liquid drops to or below its vapor pressure, the liquid rapidly evaporates, forming vapor bubbles. These bubbles then move and collapse violently within

Earth's Gravitational Field

The gravitational field of the Earth is the disturbance that occurs in the space surrounding a body having mass. The intensity of the gravitational field at a point in space is the force with which the Earth attracts a unit mass located at that point. The weight of a body is the force with which the Earth attracts it. The gravitational potential energy of a mass m at a point in Earth's gravitational field is the work performed by the gravitational field to move the mass m from that point to infinity. The gravitational potential at a point in Earth's gravitational field is the work performed by the gravitational field to move the unit mass from that point to infinity.

• Period of revolution: Time it takes a satellite

Center of Buoyancy

The center of buoyancy is the center of gravity of the volume of water displaced by a float for a given condition. Also known as the center of thrust, as it is, for the purpose of stability, which regards the force applied. It is represented by the letter C and in some publications with the letter B to equate the "Center of Buoyancy" of English.

Since the ship moves in waves, the position of the center of buoyancy is variable and depends on the hull shape and volume submerged at that time. The curve in the transverse plane that describes the center of buoyancy for different angles of rocking is called the curve, and its center of buoyancy ray radii.

Transverse Metacentric

Since by definition the metacenter is in the vertical... Continue reading "Understanding Ship Stability and Maritime Forces" »

1. What is an Electrical Accident?

An electrical accident is a process in which a person receives electrical energy, either directly or indirectly. This can range from simple electromagnetic radiation to situations where the victim becomes electrically coupled to the network.

2. Definition of Electrical Contact

Electrical contact refers to the probability of a human body being subjected to a potential difference, resulting in an electric shock due to the passage of current through it.

3. Physiological Effects of Electrical Current Above 5A

When an electrical current exceeding 5A passes through the human body, the following physiological phenomena may occur:

• Less than one cardiac cycle: Ventricular fibrillation, early electrocution (depending on the

Aqueous Humor

The aqueous humor is the first medium that light travels through, limited by the cornea. Behind it is the lens, which is a convex lens. Finally, the vitreous humor is the fluid that fills the eyeball.

Eyeball Structure

The eyeball has three layers:

1. Sclera: The outer membrane, very hard, protects the eye. It is white and opaque to the passage of light, except for the cornea.
2. Choroid: Dark in appearance. It contains the iris, which controls the passage of light by opening or closing the pupil.
3. Retina: The innermost layer, formed by light-sensitive nerve cells called rods and cones.

Accommodation of the Eye

Distance vision is possible through the lens. If an object is at infinity, the lens is at rest. To focus on closer objects, the ciliary... Continue reading "Understanding the Human Eye and Common Vision Conditions" »

Venturi Meter

A Venturi meter has two entrances at each end, along with a nozzle. Fluid passes through the nozzle, typically made from a single casting. Key components include:

• An upstream section with the same diameter as the pipe, fitted with a brass ring containing piezometric openings to measure static pressure.
• A converging tapered section leading to a cylindrical throat, also equipped with a brass piezometer ring.
• A diverging conical section that gradually expands back to the original pipe diameter. Piezometer rings connect to a differential manometer at each end.

Venturi meter size is specified by the pipe diameter and throat diameter (e.g., a 6"x4" Venturi fits a 6" pipe and has a 4" throat).

For accurate measurements, the Venturi meter... Continue reading "Fluid Flow Measurement: Venturi, Orifice & Pitot Tube" »