Physics Chapter on States of Matter and Stress

Module 02 - Physics

• This module covers various physics topics related to maintenance training.
• Aviotrace Swiss SA is the publisher of this training material.
• The copyright is held by Aviotrace Swiss SA, 2020.
• The document is part of a 147 Maintenance Training Organisation.

Topic: Matter

• Matter is anything that occupies space and has mass.
• The Law of Conservation of Matter states matter cannot be created or destroyed; only its characteristics can change.
• State changes involve energy conversion.
• Atoms are held together by electrical fields generated by the nucleus (positive charge) and electrons (negative charge).
• Electrons are much lighter than protons (approximately 1850 times less massive).
• The negative charge of electrons balances the positive charge of protons in an atom.
• Neutrons, with neutral charge have the same mass as protons.

Topic: Bohr's Atomic Model

• Electron paths around the nucleus are determined by the number of particles in the nucleus and the energy level of each electron, organized in shells (K, L, M, N...).
• Each shell has a maximum number of electrons (2n²).
• The shells are assigned letters (K, L, M, N...)

Topic: Chemical Compounds

• There are 109 different elements (atoms).
• A compound consists of two or more elements combined.
• Elements are identified by their atomic number and atomic mass.
  • Atomic number is the number of protons in the nucleus.
  • Atomic mass is the sum of protons and neutrons.

Topic: Physical States (Solids, Liquids, Gases)

• Solids have particles tightly packed in fixed positions, maintaining their shape.
• Giving heat energy to a solid increases molecular motion, causing particles to move away from their fixed positions, changing to a liquid state.
• Liquids adapt to the shape of their containers; their volume remains roughly constant.
• Continued heat input in liquids increases molecular motion, overcoming surface tension and transforming to a gaseous state.
• Gases have no definite shape or volume, easily filling their containers.

Topic: Change Between States

• Fusion: transformation of solid to liquid.
• Consolidation: transformation of liquid to solid.
• Evaporation: transformation of liquid to gas (vapor).
• Condensation: transformation of gas to liquid.
• Sublimation: transformation of solid to gas, or vice-versa.
• The triple point is the temperature and pressure point where all three states (solid, liquid, gas) of matter coexist in equilibrium.
• Latent heat is the energy absorbed or released during a change of state without a change of temperature.
• Latent heat of fusion is the energy for a solid-to-liquid phase transition.
• Latent heat of vaporization is the energy for a liquid-to-gas phase transition.

Topic: Mechanics

• Fundamental Units: Length (meter), Mass (kilogram), Time (second), Electric current (ampere), Temperature (Kelvin), Luminous intensity (candela), Amount of substance (mole).
• Secondary Units: Density (kg/m³), Force (Newton), Energy (Joule), Pressure (Pascal), Power (Watt).
• SI Prefix Multiple (used for easier notation of large and small values).
• Force: Any change in the state of rest or motion of a body.
• Moments and Couples: forces causing rotation.
• Stress: the force applied to a body per unit area. Stress types: tension, compression, torsion, flextion, and shear.

Topic: Hooke's Law

• Hooke's Law describes the relationship between stress and strain in elastic materials.
• The stress is directly proportionate to the strain.
• The constant of proportionality (E) is called Young's Modulus.

Topic: Pressure

• Pressure is defined as force per unit area. The unit is Pascal.
• Pressure is the same in all directions in a fluid, and perpendicular to container sides.
• Indicated pressure, Absolute pressure, and Differential pressure are different types of pressure measurements.

Topic: Velocity

• Velocity is the rate at which an object changes its position.
• Velocity in the International System is measured in meters per second (m/s).

Topic: Acceleration

• Acceleration is the rate at which an object changes its velocity.
• Instant acceleration is the measure of acceleration at any given point in time.
• When an object is slowing down (decelerating), acceleration has a negative value.
• Acceleration in the International System is measured in meters per square second (m/s²).

Topic: Uniform Linear Motion

• Uniform linear motion is when an object moves in a straight line at constant speed.
• Distance equals velocity multiplied by time (S = Vt).

Topic: Uniformly Accelerated Motion

• A constantly accelerating object has a velocity that changes at a constant rate.
• Velocity (V) is calculated using the acceleration (a) and the time (t). (V = at)
• Equation (V = at) is used in velocity-time graphs.

Topic: Free-Falling Object

• A free-falling object is a case of uniformly accelerated motion under the influence of gravity.
• The acceleration due to gravity (g) is approximately 9.81 m/s².
• Equations for calculating distance (s) and velocity (V) using the time (t) under free-falling motion are given.

Topic: Uniform Circular Motion

• Uniform circular motion occurs when an object moves at a constant speed in a circular path.
• Related terms: velocity (V), period (T), frequency (f), centripetal acceleration (a).
• Calculation for Tangential velocity ( V=2πr/T) and centripetal acceleration (a=V²/r)

Topic: Angular Velocity

• Angular velocity (ω) is the rate of rotation of an object in a circle. Units are radians per second [rad/s].

Topic: Vibration

• Vibration is a mechanical oscillation about an equilibrium point, either periodic (harmonic) or non-periodic (random).
• Vibration is often undesirable, causing energy dissipation and noise.
• Mechanical vibrations are a measure of stiffness(spring constant, k).

Topic: Spring

• Springs obey Hooke's Law, with the extension of the spring being directly proportional to the applied force.
• The spring constant, k, is a measure of the spring's stiffness.

Topic: Spring: Free Vibration Without Damping

• The equation for natural frequency of a mass-spring system is fn=1/2π√(k/m).

Topic: Spring: Free Vibration With Damping

• Damping coefficient.

Topic: Mechanical Advantage

• Mechanical advantage is the ratio of weight moved to the stress applied.
• Machines like levers, inclined planes, pulleys, and gears are used to reduce the force required to move heavy objects thus increasing the mechanical advantage.

Topic: Levers

• Three classes of levers are described, distinguished by the relative positions of the fulcrum, force, and load, and their mechanical advantages.

Topic: Pulley

• Pulleys are simple machines that can help achieve mechanical advantage.
• Single fixed pulleys have a mechanical advantage of one.
• Multiple or movable pulley systems have a higher mechanical advantage than one.

Topic: Force And Heat;

• Force changes or tries to change rest or motion.
• Heat is energy transfer due to a temperature difference.
• Units: Joule (J) and calorie (Cal).
• Heat transfer types: radiation, convection, conduction.

Topic: Efficiency

• Efficiency is a dimensionless quantity (between 0 and 1) which expresses the ratio of output (power or work) vs Input (power or work).
• The formula for efficiency is η = (power out)/(power in). Calculate power using the relevant formulas.

Topic: Kinetic Energy

• Kinetic energy is the energy of motion of a body.
• Kinetic energy is directly proportional to the mass and the square of the velocity: Ek=1/2 mv².

Topic: Potential Energy

• Potential energy is energy stored due to position.
• Gravitational potential energy (Ep) is calculated as Ep = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height.

Topic: Mechanical Energy

• The sum (total) of energy is constant during the movement of a body and is referred to as Mechanical Energy.

Topic: Law of Dynamics: First Law

• Newton's First Law: A body at rest will remain at rest and a body in uniform motion will maintain that motion unless acted upon by an unbalanced force.
• Inertia: The resistance of a body to change its state of motion.

Topic: Law of Dynamics: Second Law

• Newton's Second Law: The force acting on a body is equal to the product of the mass and the acceleration of the body: F = ma.

Topic: Law of Dynamics: Third Law

• Newton's Third Law: For every action, there is an equal and opposite reaction.

Topic: Impulse

• Impulse is the product of force and the time interval over which the force acts: (I = F∆t).

Topic: Momentum

• Momentum (p) is the product of mass (m) and velocity (v): p = mv.
• The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it.
• The change of momentum = Impulse.

Topic: Friction

• Friction is a force that opposes motion between surfaces in contact.
• Three types of friction: Sliding, rolling, and fluid friction.
• Static friction: opposes the initiation of motion.
• Dynamic (or Kinetic) friction: opposes motion once it has started.
• Limiting friction: The maximum static friction a surface can endure before slipping occurs.

Topic: Rolling Friction

• Rolling friction occurs when a body rolls on a surface.
• It is caused by rolling friction of the rotation axis and the contact area between the object that rolls and the surface.

Topic: Density

• Absolute density is the ratio of an object's mass to its volume ( ρ=m/v).
• Density units are kg/m³.
• Relative density is the ratio of an object's density to the density of a reference substance, usually water at 4°C.

Topic: Density of air

• Air density is affected by temperature and pressure, with density being inversely proportional to temperature and directly proportional to pressure.

Topic: Specific Weight

• Specific weight is the ratio of weight (W) to volume (V) of a substance and the units are N/m³.
• Relative specific weight is calculated by dividing the weight of the body to the weight of the water, and is equal to the density of the substance.

Topic: Fluids: Viscosity and Fluid Resistance

• Viscosity: fluid resistance to flow. Depends on fluid type and temperature.
• Drag: resistance to motion through a fluid, dependent on velocity. Profile drag is the sum of form drag (due to object shape) and skin drag.

Topic: Bernoulli's Theorem

• Bernoulli's Theorem: constant sum of static and dynamic pressure in a moving fluid.
• It can be used to calculate dynamic pressure and flight speed.

Topic: Venturi's Tube

• Venturi effect: pressure increases in a fluid flow when velocity decreases.

Topic:Chapter 02.03 Thermodynamics

• This chapter details the fundamental concepts of thermodynamics.

Topic: Temperature

• Temperature is a measure of thermal energy.
• Thermal equilibrium occurs when there's no heat exchange between systems.
• Temperature scales: Kelvin, Celsius, Fahrenheit. Unit conversion formulas are given.

Topic: Heat Transfer

• Heat transfer is energy flow due to a temperature difference.
• Three types of heat transfer: radiation, convection, conduction.

Topic: Heat

• Heat is energy transferred due to a temperature difference.
• Heat is measured in Joules(J).
• Heat capacity is the measure of heat energy required to increase temperature of a body of 1 K (or 1°C)

Topic: First Law of Thermodynamics

• The net Heat Energy (Q) transferred into a system minus the net Work Energy (W) done by a system is equal to the change in internal energy (ΔU). Q – W = ΔU

Topic: Second Law of Thermodynamics

• There are two theorems that detail aspects about heat engines, such as impossibility of converting total heat energy into work.
• No process has the sole result of transferring heat from a cooler to a hotter object.

Topic: Gases

• Boyle's Law: The volume of a gas at a constant temperature varies inversely with its pressure.
• Charles' Law: The volume of a gas at constant pressure varies directly with its absolute temperature.
• Pressure Law: The pressure of a gas at constant volume varies directly with its absolute temperature.
• Adiabatic process: No heat is exchanged.

Topic: Perfect Gas

• Perfect gas law: pV = nRT.
• Laws of perfect gases are admitted.
• Properties of perfect gases: molecules as points, elastic interactions, no intermolecular forces.

Topic: Work Done by a Gas During Expansion

• Work done by a gas is calculated through the formula Work = P * ∆V

Topic: Cycle of Operation

• Closed systems that go through a cycle return to their original state.
• The heat input equals total work output plus any wasted heat.

Topic: Optics (Light)

• Light's nature: Newton's corpuscular, Huygens' wave theories. Wave and particle duality explained by modern physics. (Quantum Mechanics).
• Electromagnetic Spectrum parameters: frequency and wavelength and examples. The visible light spectrum (with bands like Infrared, Visible, Ultraviolet).
• Speed of light in a vacuum, air are approximately the same, but reduce slightly inside mediums.
  • Refractive index relates to this speed reduction.

Topic: Reflection and Refraction

• Reflection occurs when light bounces off a surface. The angle of incidence equals the angle of reflection.
• Refraction occurs when light bends as it passes between mediums with differing refractive indices. Snell's Law describes the relationship between angles and refractive indices.

Topic: Fiber Optics

• Fiber optics uses total internal reflection to transmit light through hair-thin glass fibers.
• Fiber Optic structure components: Jacket, Cladding, Core.
• Two types of fibers are used; multi-mode and single-mode.

Topic: Wave Motion and Sound

• Wave motion: a disturbance that spreads in space, carrying energy.
• Types of waves: Transverse, longitudinal.
• Wave parameters: length and amplitude. Wave velocity related to its frequency (lambda/T) and inverse of the frequency (C/f).
• Sound: the sensation caused by wave motion; frequency measured in Hertz.

Topic: Doppler Effect

• Doppler effect: apparent change in frequency or wavelength of a wave from a moving source relative to an observer. Example with an ambulance.

This quiz covers key concepts related to the states of matter, including the behavior of solids, liquids, and gases under heat energy. It also explores mechanical properties such as stress and the characteristics of vectorial and scalar magnitudes. Test your understanding of these fundamental principles in physics.