What are the SUVAT equations of motion? — s = displacement, u = initial velocity, v = final velocity, a = acceleration, t = time. The five equations: v = u + at. s = ut + ½at². s = vt − ½at². v² = u² + 2as. s = ½(u+v)t. Used when acceleration is constant.

What is Newton's First Law of motion? — An object remains at rest or in uniform motion in a straight line unless acted upon by an unbalanced (net) external force. This is the law of inertia. Example: a spacecraft in deep space continues moving at constant velocity with no engines.

What is Newton's Second Law of motion? — F = ma — the net force on an object equals its mass times its acceleration. Alternatively: Force = rate of change of momentum (F = Δp/Δt). If mass is constant: F = ma. Units: Newtons (N = kg·m/s²).

What is Newton's Third Law of motion? — For every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B simultaneously exerts an equal and opposite force on object A. The forces act on different objects — they never cancel each other out.

What is momentum and its formula? — p = mv (momentum = mass × velocity). A vector quantity — has direction. Units: kg·m/s or N·s. Conservation of momentum: In a closed system, total momentum before = total momentum after a collision.

What is impulse and how does it relate to momentum? — Impulse = F × Δt = Δp (change in momentum). A large force applied for a short time produces the same impulse as a small force applied for a longer time. Explains why airbags and crumple zones save lives — they increase collision time → reduce peak force.

What is the difference between elastic and inelastic collisions? — Elastic: Both momentum AND kinetic energy are conserved. Objects bounce off perfectly — no deformation. Ideal (rare). Inelastic: Momentum is conserved but kinetic energy is NOT (converted to heat, sound, deformation). Real collisions are inelastic. Perfectly inelastic: Objects stick together — maximum KE loss.

What is the formula for gravitational potential energy (GPE)? — GPE = mgh where m = mass (kg), g = gravitational field strength (9.81 m/s² on Earth), h = height above reference point (m). Units: Joules (J). GPE increases as height increases.

What is the formula for kinetic energy (KE)? — KE = ½mv² where m = mass (kg), v = velocity (m/s). Units: Joules (J). KE is proportional to the square of velocity — doubling speed quadruples KE.

What is the principle of conservation of energy? — Energy cannot be created or destroyed — only converted from one form to another. The total energy of an isolated system remains constant. Example: GPE converts to KE as an object falls: mgh = ½mv² (ignoring air resistance).

What is work (in physics) and its formula? — W = Fd cos θ where F = force (N), d = displacement (m), θ = angle between force and displacement. Work is done only when the force has a component in the direction of motion. Units: Joules (J). No work is done if displacement is zero or force is perpendicular to motion.

What is power and its formula? — P = W/t = Fv where P = power (W), W = work done (J), t = time (s), F = force, v = velocity. Power is the rate of doing work or transferring energy. Units: Watts (W = J/s).

What is efficiency? — Efficiency = (useful energy output / total energy input) × 100%. No real machine is 100% efficient — energy is always lost (usually as heat). Efficiency < 1 (or < 100%). Improving efficiency reduces energy losses.

What is projectile motion? — The curved path followed by an object launched into the air under gravity alone (no air resistance). Horizontal: constant velocity (no horizontal force). Vertical: constant downward acceleration (g = 9.81 m/s²). The two components are independent — treat separately.

What is circular motion and what provides the centripetal force? — An object moving in a circle at constant speed is constantly changing direction → it is accelerating (centripetal acceleration toward centre). Centripetal force F = mv²/r = mω²r — always directed toward the centre. Provided by: gravity (planets), tension (string), normal force (car rounding a bend), friction (tyres).

What is centripetal acceleration? — a = v²/r = ω²r — directed toward the centre of the circular path. Even at constant speed, an object in circular motion is accelerating because its direction is changing. The centripetal force is what produces this centripetal acceleration.

What is simple harmonic motion (SHM)? — Oscillatory motion where the restoring force is proportional to and directed opposite to the displacement from equilibrium: F = −kx. Examples: mass-spring system, simple pendulum (small angles). Characteristics: sinusoidal displacement, constant amplitude (no damping), fixed period.

What is the period of a simple pendulum? — T = 2π√(L/g) where L = length (m), g = gravitational field strength (m/s²). Period is independent of mass and amplitude (for small angles). Increasing length increases period. Used in clocks.

What is friction and what are its two types? — A force opposing relative motion between surfaces. Static friction: Prevents motion from starting — can vary up to a maximum value. Kinetic (sliding) friction: Acts when surfaces are sliding — usually constant and less than maximum static friction. f = μN where μ = coefficient of friction, N = normal force.

What is the difference between mass and weight? — Mass: The amount of matter in an object — scalar, measured in kg, constant everywhere. Weight: The gravitational force on an object — vector, measured in Newtons. W = mg where g varies by location (9.81 m/s² on Earth, 1.62 m/s² on the Moon).

What is the principle of moments? — For a body in rotational equilibrium: Sum of clockwise moments = Sum of anticlockwise moments. Moment = Force × perpendicular distance from pivot. Units: N·m. Used to solve problems with levers, beams, and seesaws.

What is Hooke's Law? — The force needed to extend or compress a spring by some distance is proportional to that distance (within the elastic limit): F = kx where k = spring constant (N/m) and x = extension or compression (m). Beyond the elastic limit, the spring is permanently deformed.

What is the terminal velocity of a falling object? — The constant maximum velocity reached when the drag force equals the weight of the object — net force = 0, so acceleration = 0. Factors: heavier objects have higher terminal velocity; streamlined shapes reduce drag → higher terminal velocity. Parachute greatly increases drag → very low terminal velocity.

What is gravitational field strength (g) and how does it vary? — The force per unit mass at a point in a gravitational field: g = F/m (N/kg or m/s²). On Earth's surface: g ≈ 9.81 m/s². Decreases with distance from Earth (g ∝ 1/r²). At the Moon's surface: ~1.62 m/s². In space far from any body: ≈ 0.

What are Newton's Law of Universal Gravitation? — Every mass attracts every other mass: F = Gm₁m₂/r² where G = 6.67 × 10⁻¹¹ N·m²/kg² (universal gravitational constant), m₁ and m₂ = masses, r = distance between centres. Force decreases as inverse square of distance. Acts along the line joining the centres.