Part-66 Module 2: physics laws and formulas for B1

Module 2 is 52 multiple-choice questions in 65 minutes for category B1. Many questions apply one formula to simple numbers, using g = 9.81 m/s².

Statics

• Weight W = mg; a 10 kg mass weighs 98.1 N.
• Moment = force × perpendicular distance; in equilibrium, clockwise moments equal anticlockwise moments.
• Forces at right angles combine by Pythagoras; a force F at angle θ has components F cos θ and F sin θ.
• Stress = force / area; strain = extension / original length; Young's modulus = stress / strain. Hooke's law holds up to the elastic limit.
• Pressure = force / area; in a liquid p = ρgh. Pascal's principle makes hydraulic presses multiply force by the area ratio. Archimedes: upthrust equals the weight of fluid displaced. Absolute pressure = gauge + atmospheric.

Kinetics and machines

• v = u + at, s = ut + ½at², v² = u² + 2as. A dropped object reaches 29.43 m/s after 3 s.
• Centripetal force = mv²/r; v = ωr; rpm × 2π / 60 gives rad/s.
• A pendulum's period T = 2π√(l/g) does not depend on mass.
• Mechanical advantage = load / effort; velocity ratio = effort distance / load distance; efficiency = MA / VR.

Dynamics

• F = ma. Work = force × distance; power = work / time = force × velocity.
• Potential energy mgh; kinetic energy ½mv² (double the speed, four times the energy).
• Momentum mv is conserved in collisions; impulse = force × time = change in momentum.
• Gyroscopes: rigidity in space (attitude indicator) and precession 90° in the direction of rotation (turn indicator).
• Coefficient of friction μ = friction force / normal force; static friction exceeds sliding friction.

Fluids

Specific gravity × 1,000 kg/m³ gives density. Continuity: A₁v₁ = A₂v₂. Bernoulli: faster flow has lower static pressure, as in a venturi. Dynamic pressure q = ½ρv². Liquid viscosity falls as temperature rises; gas viscosity rises.

Thermodynamics

• K = °C + 273. Q = mcΔT for sensible heat and Q = mL for latent heat.
• Heat moves by conduction, convection and radiation; only radiation crosses a vacuum.
• Linear expansion ΔL = αLΔT.
• Gas laws (absolute temperature and pressure): Boyle P₁V₁ = P₂V₂; Charles V ∝ T; pressure law P ∝ T; combined PV/T constant.
• Adiabatic compression heats a gas; the Otto cycle adds heat at constant volume, the Brayton cycle at constant pressure.

Light and sound

Light travels at about 3 × 10⁸ m/s; angle of incidence equals angle of reflection; refractive index n = c/v; total internal reflection makes fibre optics work. Sound is a longitudinal wave needing a medium; v = fλ; pitch follows frequency, loudness follows amplitude; the Doppler effect raises pitch as a source approaches.