Notes, abstracts, papers, exams and problems of Physics

The History of Parachutes

Early Attempts

The first known attempt at parachuting occurred in Cordova, Spain, in 852. Abbás Ibn Firnás jumped from a tower with a large cloak, but suffered injuries upon landing. Leonardo da Vinci also proposed the use of parachutes in the 15th century.

The First Practical Parachute

The first practical parachute was invented in 1783 by Louis-Sébastien Lenormand. In 1785, Jean Pierre Blanchard successfully used a parachute to save a dog from a fall. In 1793, he became the first person to successfully use a parachute for a human descent.

Parachutes in Aviation

Parachutes became a standard part of hot air balloon equipment in the 19th century. After World War I, they were adopted as safety systems for pilots and passengers... Continue reading "The Evolution of Parachutes: From Ancient Attempts to Modern Safety Systems" »

Space Vocabulary

Here are some common space-related terms and their definitions:

• Satellite: A man-made object intentionally placed into orbit.
• Atmosphere: The gases surrounding a planet.
• Gravity: The force that attracts a body toward the center of the Earth, or toward any other physical body having mass.
• Capsule: A small, detachable compartment of a spacecraft.
• Cosmonaut: A Russian astronaut.
• Orbited: Moved in a circular path around a celestial body.
• Re-entering: Returning to the Earth's atmosphere.
• Spacecraft: A vehicle designed for travel in space.
• Touchdown: The moment when an aircraft or spacecraft lands.
• Mission: An important assignment carried out for political, religious, or commercial purposes, typically involving travel.
• Space Shuttle: A reusable

Permanent Magnet

: once magnetized, remains magnetized. Ferromagnet: easily magnetized (iron, nickel, cobalt, some rare-earth metals, magnetite). Paramagnet: magnetized with more difficulty. Diamagnet: repels magnetic fields (slightly) - “not magnetic”./Materials can be broken into smaller chunks, called “domains”. Each domain has a miniature magnetic field. Materials may look the same, but at a smaller level, domains could be different - hence why some are magnets (or magnetize easily) and some don’t. Material, Temperature, Condition, Size & Shape*, Distance, affects magnet strength. All magnets* have two poles; North and South. At poles magnet is at its strongest (repelling or attracting). Breaking a magnet turns into 2 smaller... Continue reading "Understanding Magnetism, Electricity, and Light: A Comprehensive Overview" »

Parabolic Motion

Is when an object has two dimensions: U.R.M on the horizontal axis and U.A.R.M on the vertical axis.

Vertical Motion

Is when we throw an object totally up, meaning that the initial velocity or force is only applied in the vertical axis.

Uniform Rectilinear Motion (U.R.M)

Is when an object travels in a straight line at a constant speed with zero acceleration.

Uniformly Accelerated Rectilinear Motion (U.A.R.M)

Is when an object travels in a straight line with constant acceleration.

Inertia

Property of objects to maintain their current state.

Law of Conservation of Matter

Energy is neither created nor destroyed, only transformed.

Gravitational Acceleration

Type of acceleration that attracts bodies towards the center of an astro.

Work

Scalar... Continue reading "Laws of Motion and Gravitation in Physics" »

1) What reason does Michael give for choosing the company where he works?

1. TD principles

Fundamentals of HVAC Duct Systems

• Pressure Measurement: Duct system pressure is measured in inches of water column (in. WC).
• Blower Function: The blower creates pressure to force air through the duct system, conditioning equipment, and into the room.
• Atmospheric Pressure: Standard atmospheric pressure is 14.696 psi.
• Manometer Usage: A manometer measures air velocity pressure in a duct.
• Airflow Measurement Tools: Anemometers or velometers are commonly used to measure airflow in air distribution systems.
• Airflow Check: Airflow can be checked by feeling it 2-3 feet from a register.
• Forced-Air vs. Natural-Draft: Forced-air systems use a blower, unlike natural-draft systems.
• Duct Pressure Components: Duct pressure equals velocity pressure plus static pressure.

Electricity

The smallest part in which matter can be divided is the atom. Its construction is like this:

Nucleus: protons - mass and positive charge / neutrons - mass and negative charge

Orbits of electrons: they do not have mass but they have negative electric charge

Electric charge is a property of subatomic particles which influences the action of forces between items.

Charges of the same sign repel each other / Charges of different signs attract each other

1 coulomb = 6.25x10^18 electrons / The atoms of an object can lose electrons and become charged / The atoms of an object can gain electrons and become charged / Electric current is the flow of electrons through a conductor material

An Electric Device

1) An electric device has a resistance of

Example 2: Find parametric equations for a particle that starts at (0, 3, 0) and moves around a circle as shown in Figure 17.1. The circle has a radius of 3 in the yz-plane, centered at the origin.

Solution: Since the motion is in the yz-plane, we have x = 0 at all times t. Looking at the yz-plane from the positive x-direction, we see motion around a circle of radius 3 in the clockwise direction. Thus, the parametric equations are:

• x = 0
• y = 3cos(t)
• z = -3sin(t)

Example 3: Describe in words the motion given parametrically by x = cos(t), y = sin(t), z = t.

Solution: The particle's x- and y-coordinates give circular motion in the xy-plane, while the z-coordinate increases steadily. Thus, the particle traces out a rising spiral, like a coiled spring.... Continue reading "Parametric Equations: Lines, Circles, and Motion in 3D Space" »

Vocab. 1

:

• go shopping
• hang out (penjar)
• listen to music
• play computer games
• read a magazine
• surf the net (navegar)
• watch sport on TV
• dull (avorrit)
• enjoyable (agradable)
• exciting
• frustrating
• interesting
• relaxing
• average (mitjana)
• correlation
• less than half (menys de la meitat)
• majority
• minority
• percentage
• survey (enquesta)

Vocab. 2

:

• adventure
• characters (personatges)
• context
• fantasy
• legend
• myth (mite)
• plot (trama)
• scene
• science fiction
• sript (guió)
• story
• tale (conte)
• angry
• comical
• courageous
• cowardly
• resourceful (ingeniós)
• sentimental
• spiteful (malèvol)
• genre
• metaphore
• moral
• setting (configuració)
• simile
• synopsis
• check over (revisar)
• come to
• come up with (presentar)
• work at
• go back to
• get across
• turn over (entregar)
• write down (apuntar-se)
• carefully
• completely
• convincingly
• daringly (atrevidament)