Free EASA Part-66 Module 2 Exam Flashcards

A proton has positive charge and a neutron has no net charge; both are in the nucleus. An electron has negative charge and occupies the surrounding electron cloud. A neutral atom has equal numbers of protons and electrons.

Atomic number is the number of protons and identifies the element. Mass number is the total number of protons plus neutrons in one isotope. Changing neutron count changes the isotope, not the element.

An element contains one type of atom. A compound contains elements chemically bonded in a fixed ratio. A mixture combines substances without fixed chemical bonding, so physical methods can separate its components.

A molecule is an electrically neutral group of atoms held together by chemical bonds. An ion is an atom or bonded group with net charge: electron loss forms a positive ion, while electron gain forms a negative ion.

A solid keeps shape and volume because particles vibrate about fixed positions. A liquid keeps volume but flows to the container's shape. A gas has neither fixed shape nor fixed volume and expands to fill its container.

For a force F at angle θ from the positive x-axis, Fx = F cos θ and Fy = F sin θ. Components are signed vectors; their resultant recreates the original force by vector addition.

A body is in static equilibrium only when the vector sum of forces is zero and the sum of moments about any point is zero. Zero force prevents linear acceleration; zero moment prevents angular acceleration.

A force moment is M = Fd, where d is the perpendicular distance from the pivot to the force's line of action. A couple is two equal, opposite, separated forces: its net force is zero but it produces a pure turning moment.

The centre of gravity is the point through which the body's resultant weight acts. Stability improves when the centre of gravity is lower and the support base is wider; overturning begins when its vertical line falls outside that base.

Normal stress is load per original cross-sectional area, σ = F/A, measured in pascals. Normal strain is fractional length change, ε = ΔL/L, and is dimensionless. Stress describes loading; strain describes deformation.

Within the proportional elastic region, stress is proportional to strain: σ = Eε, where E is Young's modulus. Remove the load there and the material recovers; beyond the elastic limit, permanent deformation may remain.

Gauge pressure at depth h is p = ρgh, so it rises with density and depth. The resulting pressure difference creates an upward buoyant force equal to the weight of fluid displaced by the immersed body.

Speed is the scalar rate of distance travelled. Velocity is the vector rate of displacement, so it includes direction. An object can have constant speed while its velocity changes, as in uniform circular motion.

For constant acceleration a: v = u + at, s = ut + ½at², and v² = u² + 2as. Choose a positive direction first and keep the signs of velocity, displacement, and acceleration consistent.

Ignoring air resistance, every object has the same downward acceleration g, about 9.81 m/s² near Earth's surface. Mass does not change this acceleration; drag is what makes real falling objects behave differently.

For speed v on radius r, centripetal acceleration is a = v²/r and points toward the centre. The required resultant force is F = mv²/r; 'centrifugal force' is not an outward interaction force in an inertial frame.

Period T is time for one cycle; frequency f is cycles per second in hertz. They are reciprocals: f = 1/T. Angular frequency is ω = 2πf, measured in radians per second.

Resonance occurs when a periodic driving frequency is at or near a system's natural frequency, producing a large response when damping is low. Changing stiffness, mass, damping, or forcing frequency changes the response.

If no resultant external force acts, a body remains at rest or continues with constant velocity. Inertia is the resistance to a change in motion, and mass measures that inertia.

The resultant external force equals the rate of change of momentum. For constant mass, ΣF = ma. Acceleration has the direction of the resultant force, not necessarily the direction of motion.

When body A exerts a force on body B, B simultaneously exerts an equal-magnitude, opposite-direction force on A. The pair acts on different bodies, so the two forces do not cancel on either body's free-body diagram.

Translational kinetic energy is ½mv² and gravitational potential energy near Earth is mgh. If only conservative forces do work, their sum stays constant; friction transfers mechanical energy into internal energy.

Work by a constant force is W = Fs cos θ. Power is the rate of doing work, P = W/t. Efficiency = useful output energy or power ÷ input energy or power; a real machine's efficiency cannot exceed 1 or 100%.

Momentum is p = mv. It is a vector, so its direction follows velocity, and its SI unit is kg·m/s. A small fast mass can have the same momentum as a larger slow mass.

Impulse J equals the change in momentum: J = Δp. It also equals the area under a force-time graph. For the same momentum change, increasing stopping time reduces the average impact force.

Total momentum of a system remains constant when the net external impulse is zero. Internal forces can redistribute momentum between objects, but they cannot change the isolated system's total vector momentum.

Both collision types conserve total momentum in an isolated system. An elastic collision also conserves total kinetic energy; an inelastic collision converts some kinetic energy to deformation, heat, or sound, and perfectly inelastic bodies stick together.

Mass measures inertia in kilograms and does not depend on local gravity. Weight is the gravitational force W = mg in newtons, so it changes if gravitational acceleration changes.

Density is mass per volume, ρ = m/V, with SI unit kg/m³. Relative density is the ratio of a substance's density to a reference density, commonly water for liquids and solids, so it has no unit.

Viscosity measures resistance to flow. For most liquids, viscosity decreases as temperature rises; for gases, viscosity generally increases. Always identify the fluid type before predicting the temperature effect.

In an incompressible model, density is treated as constant. Gas density can change substantially with pressure and temperature, so compressibility matters especially when pressure changes or flow speeds are high; liquids are often approximated as incompressible.

Static pressure is the fluid's local thermodynamic pressure. Dynamic pressure is q = ½ρv². Along the same streamline in ideal, steady, incompressible flow at one elevation, total pressure is their sum, so increasing speed corresponds to lower static pressure.

T(K) = T(°C) + 273.15. A temperature interval of 1 K equals an interval of 1 °C, but the zero points differ. Absolute zero is 0 K, equal to −273.15 °C.

Temperature describes thermal state and relates to average microscopic particle energy. Heat is energy transferred because of a temperature difference; it flows spontaneously from higher to lower temperature until thermal equilibrium.

For a temperature change without a phase change, Q = mcΔT. Here Q is heat transferred, m is mass, c is specific heat capacity, and ΔT is the temperature change. A larger c requires more heat for the same mass and ΔT.

During an ideal phase change at constant pressure, added or removed energy changes phase rather than temperature. Use Q = mL, where L is the specific latent heat for the relevant melting, vaporisation, or other transition.

Conduction transfers energy through microscopic interactions in matter. Convection transports energy by bulk fluid motion. Radiation transfers energy by electromagnetic waves and therefore does not require a material medium.

For a modest temperature change, ΔL = αL₀ΔT, where α is the material's linear expansion coefficient. Expansion gaps and differing coefficients matter because constrained or unequal expansion can create stress and distortion.

Using the convention that W is work done by the system, ΔU = Q − W. Heat added raises Q; work done by the system removes stored energy unless heat replaces it. State the sign convention because some texts define work oppositely.

For a fixed amount of ideal gas at constant absolute temperature, pressure varies inversely with volume: P₁V₁ = P₂V₂. Reducing volume therefore raises absolute pressure when temperature and gas quantity stay fixed.

At constant pressure, Charles's law gives V₁/T₁ = V₂/T₂. At constant volume, P₁/T₁ = P₂/T₂. Temperature must be absolute, normally kelvin, and pressure must be absolute in gas-law ratios.

The angle of incidence equals the angle of reflection, with both angles measured from the normal to the surface. The incident ray, reflected ray, and normal all lie in the same plane.

At a boundary, n₁ sin θ₁ = n₂ sin θ₂, with angles measured from the normal. A ray bends toward the normal when it enters a medium with higher refractive index and away when it enters a lower-index medium.

Absolute refractive index is n = c/v, where c is light speed in vacuum and v is its phase speed in the medium. Because n is a ratio of speeds, it is dimensionless; larger n means lower light speed in that medium.

A converging lens brings parallel rays toward a real focal point and has positive focal length. A diverging lens spreads parallel rays as if they came from a virtual focal point and has negative focal length under the usual sign convention.

Total internal reflection requires light to travel from higher to lower refractive index and strike at an incidence angle, measured from the normal, greater than the critical angle. A fibre core has higher index than its cladding, confining light by repeated internal reflection.

Wave speed is v = fλ, where f is frequency and λ is wavelength. When a wave enters a new medium, its source-set frequency stays constant while speed and wavelength may change.

In a transverse wave, disturbance is perpendicular to propagation. In a longitudinal wave, disturbance is parallel and forms compressions and rarefactions. Sound in air is longitudinal; electromagnetic light is transverse.

Superposition adds instantaneous displacements: in-phase waves reinforce and opposite-phase waves cancel. Opposite-travelling waves of equal frequency and amplitude can form a standing wave with fixed nodes of zero displacement and antinodes of maximum displacement.

Relative motion along the source-observer line changes observed frequency. Closing motion gives a higher observed pitch; separating motion gives a lower one. The source frequency itself does not change merely because source and observer move relative to each other.