Physics Formula Chart

Newton's First Law

Body at rest or uniform motion unless acted upon by net force

Eg: Book on table: balanced forces

Newton's Second Law

Net force = mass × acceleration

Eg: m=10 kg, a=5 m/s² → F=50 N

Newton's Third Law

Every action has equal and opposite reaction

Eg: Rocket: gas pushed down, rocket goes up

Momentum

Mass times velocity (vector)

Eg: m=5 kg, v=4 m/s → p=20 kg·m/s

Impulse

Change in momentum

Eg: F=100 N, t=0.1 s → J=10 N·s

Conservation of Momentum

Total momentum conserved in closed system

Eg: Collision problems

Equations of Motion 1

Final velocity

Eg: u=0, a=10, t=3 → v=30 m/s

Equations of Motion 2

Displacement

Eg: u=0, a=10, t=3 → s=45 m

Equations of Motion 3

Velocity-displacement relation

Eg: u=0, a=10, s=45 → v=30 m/s

Equations of Motion 4

Average velocity × time

Eg: u=0, v=30, t=3 → s=45 m

Free Fall

Acceleration due to gravity

Eg: v = gt (from rest): t=3 → v=30 m/s

Weight

Gravitational force on mass

Eg: m=70 kg → W=700 N

Universal Gravitation

G=6.674×10⁻¹¹ N·m²/kg²

Eg: Force between Earth and Moon

Acceleration due to Gravity

M=mass of planet, R=radius

Eg: Earth: g=9.8 m/s²

g at Height h

Approximate for h << R

Eg: At h=100 km, g slightly less

g at Depth d

g decreases with depth

Eg: At centre of Earth: g=0

Orbital Velocity

Speed for circular orbit

Eg: Earth orbit: v_o≈7.9 km/s

Escape Velocity

Speed to escape gravitational field

Eg: Earth: v_e≈11.2 km/s

Kepler's Third Law

T=orbital period, r=orbital radius

Eg: Planets farther from Sun have longer years

Gravitational PE

Negative: bound system

Eg: Increases (less negative) as r increases

Work–Energy Theorem

Net work equals change in KE

Eg: W=50 J, m=2 kg, u=0 → v=√50 m/s

Elastic PE (Spring)

k=spring constant, x=compression/extension

Eg: k=200 N/m, x=0.1 m → PE=1 J

Hooke's Law

Restoring force of spring

Eg: k=500 N/m, x=0.02 m → F=10 N

Elastic Collision

Both KE and momentum conserved

Eg: Billiard ball collisions

Inelastic Collision

Objects may stick together

Eg: Clay ball hitting wall

Perfectly Inelastic

Objects stick together

Eg: Bullet embedding in block

Wave Speed

Speed = frequency × wavelength

Eg: f=500 Hz, λ=0.68 m → v=340 m/s

Time Period

Period is reciprocal of frequency

Eg: f=50 Hz → T=0.02 s

Speed of Sound in Air

Increases with temperature

Eg: At 25°C: v≈346 m/s

Doppler Effect (source moving)

v_o=observer speed, v_s=source speed

Eg: Ambulance siren pitch changes

Intensity

Intensity decreases with distance squared

Eg: Double distance → quarter intensity

Resonance

Natural frequencies of pipes

Eg: Organ pipe harmonics

Coulomb's Law

Force between two charges

Eg: q₁=q₂=1 μC, r=1 m → F=9×10⁻³ N

Electric Field

Force per unit positive charge

Eg: Q=1 μC, r=1 m → E=9000 N/C

Electric Potential

Work done per unit charge

Eg: Q=2 μC, r=0.1 m → V=180000 V

Capacitance

Charge stored per volt

Eg: Q=100 μC, V=50 V → C=2 μF

Energy in Capacitor

Energy stored in capacitor

Eg: C=2 μF, V=100 V → U=0.01 J

Magnetic Force on Charge

q=charge, v=velocity, B=field, θ=angle

Eg: q=1 C, v=10 m/s, B=2 T, θ=90° → F=20 N

Magnetic Force on Wire

B=field, I=current, L=length

Eg: B=0.5 T, I=4 A, L=2 m → F=4 N

Faraday's Law

Induced EMF = rate of change of flux

Eg: ΔΦ=0.5 Wb, Δt=0.1 s → EMF=5 V

Magnetic Flux

B=field, A=area, θ=angle with normal

Eg: B=2 T, A=0.5 m², θ=0° → Φ=1 Wb

Transformer Ratio

Ideal transformer equations

Eg: N_s/N_p=10 → V_s=10V_p (step-up)

Mirror Formula

Sign convention: distances measured from pole

Eg: u=−30, f=−10 → v=−15 cm

Lens Formula

Thin lens equation

Eg: u=−30, f=20 → v=60 cm

Magnification (Lens)

Image to object height ratio

Eg: v=60, u=−30 → m=−2

Power of Lens

Dioptre (D)

Eg: f=0.25 m → P=4 D

Combined Lens Power

Lenses in contact

Eg: P₁=3 D, P₂=2 D → P=5 D

Critical Angle

n=refractive index of denser medium

Eg: Glass n=1.5 → C=41.8°

Prism Deviation

A=prism angle, n=refractive index

Eg: n=1.5, A=10° → δ=5°