General Physics & Important Equations Flashcards
- What are the base SI units for length, mass, and time?
Length: meter (m), Mass: kilogram (kg), Time: second (s).
- Name two derived SI units commonly used in physics.
Newton (N) for force, Joule (J) for work/energy (others include Watt (W), Pascal (Pa)).
- What is the difference between distance and displacement?
Distance is the total path traveled; displacement is the straight-line change in position, with direction.
- Define velocity and include its SI unit.
Velocity is the rate of change of displacement with direction; SI unit: meters per second (m/s).
- How is acceleration calculated?
a = Δv / Δt (change in velocity over time).
- State Newton’s First Law of Motion in simple terms.
An object remains at rest or moves uniformly unless acted on by an external force.
- State Newton’s Second Law of Motion.
F = m a (Force = mass × acceleration).
- State Newton’s Third Law of Motion.
Every action has an equal and opposite reaction.
- Give a real-world aviation example of Newton’s Third Law.
In a jet engine, hot exhaust gases are expelled backward, pushing the aircraft forward.
- Define weight and how it differs from mass.
Weight is the force due to gravity (W = m g), whereas mass is the amount of matter in an object.
- Write the formula for friction using μ (coefficient of friction).
F_friction = μ × F_normal.
- What is normal force?
A perpendicular contact force exerted by a surface on an object, balancing its weight (on a flat surface).
- Give a real-world example where friction is critical in aviation.
Aircraft tires rely on friction during landing to slow down on the runway.
- How is momentum defined?
p = m v (mass × velocity).
- What is impulse, and how does it relate to momentum?
Impulse = F × t = Δp (it’s the change in momentum).
- State the principle of conservation of momentum.
In a closed system, total momentum before an interaction equals total momentum after the interaction.
- Provide an aviation scenario where momentum is important.
During in-air refueling, the combined momentum of tanker + receiving aircraft remains conserved.
- Define work and give its formula.
Work W = F × d × cos(θ), where F is force and d is displacement.
- What is kinetic energy (KE)? Give the formula.
KE = ½ m v² (the energy of motion).
- Name a real-world aircraft example for kinetic energy.
An airplane at landing has large KE that must be dissipated by brakes/spoilers.
- What is potential energy (PE)?
Stored energy due to position or state, e.g., gravitational potential energy m g h.
- Give a real-world example of gravitational potential energy in aviation.
An aircraft at cruising altitude has large GPE that can be converted to KE during descent.
- Define power in mechanical terms.
Power (P) = Work / Time or F × v (rate of doing work).
- Why is power significant in aircraft performance?
An aircraft engine’s power output determines climb rate and overall performance.
- What does Hooke’s Law state?
F = k x (force = spring constant × extension/compression).
- Provide an aircraft example of Hooke’s Law.
Landing gear shock absorbers compress according to the applied force when the plane touches down.
- Explain stress and strain.
Stress = Force / Area, Strain = (Change in length) / (Original length).
- What is Young’s Modulus?
E = Stress / Strain, a measure of a material’s stiffness.
- Define pressure and give the formula.
P = F / A (force per unit area).
- State Pascal’s Principle.
A pressure applied to a confined fluid is transmitted equally in all directions.
- Give an aviation example of Pascal’s Principle.
Hydraulic systems (brakes, landing gear retraction) rely on fluid pressure transmission.
- What does Archimedes’ Principle describe?
An object in a fluid experiences buoyant force equal to the weight of fluid displaced.
- Provide a real-world example of Archimedes’ Principle.
A life vest increases buoyant force, helping a person float (or aircraft debris float after a ditching).
- State Bernoulli’s Principle in simple terms.
Faster fluid flow leads to lower pressure in that region of flow.
- How does Bernoulli’s Principle relate to aircraft lift?
Air moving faster over the wing’s curved surface lowers pressure on top, generating lift.
- Write the Continuity Equation for incompressible fluid flow.
A₁ v₁ = A₂ v₂ (cross-sectional area × velocity remains constant).
- What does Boyle’s Law state?
At constant temperature, for a fixed mass of gas, P ∝ 1 / V.
- State Charles’s Law.
At constant pressure, the volume of a gas is directly proportional to its temperature (in Kelvin).
- What is Gay-Lussac’s Law?
At constant volume, a gas’s pressure is directly proportional to its temperature (in Kelvin).
- Give the equation for the First Law of Thermodynamics.
ΔU = Q – W (change in internal energy = heat added – work done by the system).
- Define conduction, convection, and radiation briefly.
Conduction: heat via direct contact; Convection: heat via fluid movement; Radiation: heat via electromagnetic waves.
- What does Ohm’s Law state?
V = I R (voltage = current × resistance).
- In electrical circuits, what is electrical power?
P = V I (also I² R or V² / R).
- Give an aircraft example involving Ohm’s Law.
Designing lighting circuits in the cockpit, ensuring correct bulb current based on voltage and resistance.
- State Faraday’s Law of Induction.
An induced voltage (EMF) occurs when there is a change in magnetic flux through a conductor.
- What is Lenz’s Law?
An induced current flows in a direction that opposes the change causing it.
- Write the wave equation and define its terms.
v = f λ (velocity = frequency × wavelength).
- What is the Doppler Effect?
Change in frequency of a wave due to relative motion of source and observer.
- Give an aviation example using the Doppler Effect.
Radar systems measure aircraft or weather target speed by observing Doppler shifts in radio waves.
- Why is unit consistency (like using SI) crucial in physics calculations?
Mixing units causes errors; consistent units ensure correct, reliable results (vital in aircraft load, fuel, and performance calculations).
