Notes, abstracts, papers, exams and problems of Physics

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" »

Capacitor Function

A power capacitor stores electrical charge (electrons on one plate and ions on the other). Once charged, it maintains voltage due to electrostatic attraction. In DC circuits, it filters signals. In AC circuits, it charges and discharges in each half-cycle, delaying voltage relative to current, correcting the power factor.

Working Voltage and Breakdown

Working voltage is the maximum voltage a capacitor can withstand without dielectric damage. Breakdown voltage is the maximum voltage the dielectric can handle before failure.

Capacitor Types

• Plastic: Heavy-duty, up to 1000V, from several microfarads (µF).
• Ceramic: From picofarads (pF) to 100 nanofarads (nF), low voltage.
• Electrolytic: Polarized, high capacitance for small size (1

Scalar Product of Vectors

The scalar product of two vectors is the number obtained by multiplying the product of their magnitudes by the cosine of the angle between them. It is represented by a dot (·) and is calculated using the formula: a · b = |a| |b| cos(α).

Condition of Perpendicularity

Two vectors are perpendicular if their scalar product is zero: a ⊥ b ↔ a · b = 0.

Angle Between Vectors

The cosine of the angle between two vectors is given by: cos(α) = (a · b) / (|a| |b|).

Vector Product of Vectors

Magnitude

The magnitude of the vector product is calculated as: |a x b| = |a| |b| sin(α).

Direction

The direction is perpendicular to the plane formed by vectors a and b.

Sense

The sense is determined by applying the right-hand rule.

Kinematics:

Risks Linked to Security Conditions

The following are common risks associated with security conditions in the workplace:

• Falls of persons, both at the same level and different levels.
• Clashes with mobile and immobile objects.
• Entrapments, cuts, and projections of particles.

Preventive Measures for Security Conditions

To avoid these risks, the following measures should be implemented:

• Premises must have a minimum height of 3 meters, and offices should have a minimum height of 2.5 meters.
• Each worker must have a working space of at least 2 square meters of surface area and 10 cubic meters of volume.
• Main corridors should have a minimum width of 1.20 meters, and side corridors should have a minimum width of 1 meter.
• Passage areas and workplaces must be

Physics Formulas

Speed

V: Average velocity

• V = s / t
• s: Distance traveled
• s = v · t
• t: Time spent
• t = s / v
• Minutes to hours = min / 60

SI units:

• Speed is the distance traveled by a mobile unit per unit of time.
• m / s
• km / h
• cm / s

Acceleration

a: Acceleration

• a = V_f - V₀ / t
• V_f: Final velocity
• V_f = V₀ + a · t
• V₀: Initial velocity
• V₀ = V_f - a · t
• t: Time

SI units:

• Acceleration is the change in speed per unit of time.
• m / s²

Forces

F: Force in newtons

• F = m · a
• m: Mass in kg
• a: Acceleration in m / s²

SI units:

• Force is a physical quantity associated with movement.
• Newton (N)
• Kilogram-force (kgf)
• Pound (lb)
• Dyne (dyn)

Forces in the same direction:

• F_R = F₁ + F₂

Forces in opposite directions:

• F_R = F₁ - F₂

Mass

m: Mass in kg

• m = F / a
• F: Force in newtons
• a: Acceleration in m / s²

SI units:

San Pietro in Montorio, Bramante, 1502

Religious Architecture, Cinquecento, Rome

Introduction: This is an early work of Bramante in Rome. It is a chapel, built between 1502-1503, located in a small courtyard. According to tradition, Saint Peter was crucified on this site. It is a model of a religious building with a central plan, inspired by the Hellenistic *monopteros* temples, and its elevation recalls the Temple of the Sibyl at Tivoli.

Analysis and Features: It is considered the aesthetic ideal of the Renaissance in the 16th century. This architectural ideal is achieved by using:

• A monumental and grandiose architectural language, achieved through a rigorous study of the proportions of each part of the building.
• The creation of a complete architectural