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

Matthew Arnold's Touchstone Method of Criticism was really a comparative system of criticism.  Arnold was mostly a classicist.  He admired the ancient Greek, Roman and French authors as the models to be followed by the modern English authors.  The old English like Shakespeare, Spenser or Milton were also to be taken as models.  Arnold took selected passages from the modern authors and compared them with selected passages from the ancient authors and thus decided their merits.  This method was called Arnold's Touchstone Method.             However, this system of judgement has its own limitations.  The method of comparing passage with a passage is not a sufficient test for determining the value of a work as a whole.  Arnold... Continue reading "dsf" »

Vocabulary

• Motion: An object’s change in position relative to a reference point.
• Frame of Reference: A system for specifying the precise location of objects in space and time.
• Displacement: The change in position of an object.
• Speed: The distance traveled divided by the time interval during which the motion occurred.
• Velocity: The speed of an object in a particular direction.
• Acceleration: The rate at which velocity changes over time; an object accelerates if its speed, direction, or both change.
• Force: An action exerted on a body in order to change the body’s state of rest or motion; force has magnitude and direction.
• Friction: A force that opposes motion between two surfaces that are in contact.
• Net Force: The combination of all forces acting

LASER = Light Amplification by Stimulated Emission of Radiation

A laser is actually an oscillator rather than a simple amplifier. The difference is that an oscillator has positive feedback in addition to the amplifier.

Light is understood in a general sense: electromagnetic radiation with a wavelength around 1 μm. Thus, one can have infrared, visible, or ultraviolet lasers.

The atomic medium with population inversion used in the laser is called the active medium. The positive optical feedback is obtained by placing the active medium between two mirrors. One of them (M1) totally reflects back the light (R1 = 1) to the active medium, while the other one (M2, called the output coupler) has a reflectivity less than unity (R2 < 1) and allows some... Continue reading "Introduction to LASER Technology: Types, Operation, and Applications" »

DEFINITIONS

DISTANCE

How much ground an object has covered/traveled.

DISPLACEMENT

The change in position of an object.

SCALAR QUANTITY

Quantity that only has magnitude and no direction.

VECTOR

Physical quantity that has both magnitude and direction.

CONSTANT SPEED

Speed that does not change.

VELOCITY

Speed in a given direction.

FRAME OF REFERENCE

A background used to judge motion/speed (precise location of an object).

INSTANTANEOUS SPEED

Speed at a given moment.

ENERGY

The capacity/power to do work/move an object by applying force.

MATTER

Anything that has mass and takes up space (how much matter).

WEIGHT

Measure of how gravity pulls matter.

SPEED

Amount of distance traveled in a certain amount of time.

AVERAGE SPEED

Total distance divided by total time.

TIME DISTANCE

Application of Atomic Structure to Static Electricity

• All material objects are composed of atoms.
• An atom consists of a nucleus and a vast region of space outside the nucleus.
• The nucleus of the atom contains positively charged protons and neutral neutrons.

Charging by Friction

The frictional charging process results in a transfer of electrons between the two objects which are rubbed together.

Triboelectric Series: materiales ordenados según la capacidad de tendencia de atraer electrones.

Electrizar: cargar una sustancia/cuerpo que era neutra.

Charging by Induction

Is a method used to charge an object without actually touching the object to any other charged object.

The Electroscope

An electroscope is a device which is capable of detecting the presence... Continue reading "Static Electricity and Fundamental Electric Principles" »

Understanding Waves and Energy Transfer

A wave is a disturbance that travels a distance, carrying the energy which generated it. When the wave travels through a medium, like water or air, it does not displace the particles of the medium.

Characteristics of a Wave

• Wavelength: This is defined as the distance between two adjacent peaks or troughs of the wave. It is expressed in metres (m).
• Frequency: This is the number of oscillations or complete movements that a wave produces in one second. Its unit in SI is the Hertz (Hz).
• Speed of Propagation: This is the distance, e, that the wave travels divided by the time taken, t. It is expressed in m/s.

  Waves travel at a constant speed. Therefore:

  V_wave = e/t

  Which implies:

  e = V_wave · t

• Amplitude: This is the

Essential Wave Phenomena Definitions

Wave Terminology

• Node: A point of zero amplitude on a standing wave.
• Resonance: The increase in the amplitude of a vibration that occurs when external vibrations match an object's natural frequency.
• Antinode: A point of maximum amplitude on a standing wave.
• Standing Wave: A wave that appears to stand in one place, even though it is really two waves interfering as they pass through each other.
• Reflection: The bouncing back of an object or a wave when it hits a surface through which it cannot pass.
• Hertz (Hz): Unit of measurement for frequency.
• Frequency: The number of complete waves that pass a given point in a certain amount of time.
• Wavelength: The distance between two corresponding parts of a wave.
• Amplitude: The

Human Evolution: From *Orrorin* to *Homo Sapiens*

The Earth was formed 4,500 million years ago. There is evidence that the hominid family emerged 6 million years ago, with our species, Homo sapiens sapiens, appearing only 150,000 years ago. Our species is characterized by the development of the brain, which allows for complex social behavior, consciousness of our own existence, and a great capacity for communication. The evolution of our species includes the following:

Key Hominid Species

1. Orrorin tugenensis: Lived more than 6 million years ago (MA). They were omnivorous, lived in jungles, measured 1.4 meters, were bipedal, and were descendants of the current chimpanzees, but with differences in the pelvis, humerus, and femur.
2. Ardipithecus ramidus:

INDUCTION / magnetic flux density: the number of lines of force crossing the unit area.

Paramagnetic material: when placed in a magnetic field and become magnets are oriented in the same direction as the field. Magnetic field to cease its magnetism disappears. (weakly attracted) Cr, Al ..

Diamagnetic material: when placed inside a magnetic field, are magnetized in the opposite direction to the field. These substances are called diamagnetic and their property is called diamagnetism. (weakly repelled) Na, Cu, N, H. .. .

Ferromagnetic materials: the electron spins tend to align because of the forces between them and form small regions called domains. By placing these substances under the action of a field, partially oriented domains and grow... Continue reading "Understanding Magnetic Materials: Flux, Saturation, and Permeability" »