Physics

Mechanics

Kinematics, Newton, momentum, circular motion.

Basics

Kinematics

Relates position, velocity, and acceleration without asking what caused the force. Three equations cover constant acceleration. These are vectors: keep direction.

Newton's laws

1: If net force is zero, velocity stays (inertia). 2: F_net = ma when mass is constant. 3: Forces come in pairs, equal and opposite, on two different bodies.

Momentum

p = mv. Impulse equals Δp. With no external force, total momentum is conserved. Elastic collisions also conserve kinetic energy; inelastic ones lose some to heat or deformation.

Formulas

Constant acceleration: velocity

v = v₀ + a t

Add acceleration times time to the initial velocity.

Symbols

v₀ initial velocity
a acceleration
t time

Constant acceleration: displacement

s = v₀ t + ½ a t²

Acceleration enters with t squared.

Symbols

s displacement

Time-free relation

v² = v₀² + 2 a s

Links speed and distance when time is unknown.

Newton's second law

F_net = m a

Net force produces acceleration. Unit: N = kg·m/s².

Symbols

F_net net force
m mass

Weight

W = m g

Gravitational force. g≈9.81 m/s² near Earth. Not the same as mass.

Symbols

g gravitational acceleration

Friction

f_s ≤ μ_s N, f_k = μ_k N

Static friction up to a maximum; kinetic is usually smaller. N is the normal force.

Symbols

μ coefficient of friction
N normal force

Uniform circular motion

a_c = v² / r = ω² r, F_c = m v² / r

Speed can be constant while direction changes, so there is centripetal acceleration.

Symbols

r radius
ω angular speed (rad/s)

Impulse

J = F Δt = Δp

A larger or longer force changes momentum more.

Symbols

J impulse

In this field

Physics

Energy and work

Work, kinetic and potential energy, power, conservation.

Physics

Waves and thermodynamics

Oscillation, waves, sound, heat, entropy.

Physics

Electromagnetism and modern physics

Charge, fields, basic circuits, photons, mass–energy.

Physics

Fluids and optics

Pressure, buoyancy, Bernoulli, lenses, interference.

Physics

Relativity and nuclear sketch

Time dilation, length contraction, decay, cross-section.

Physics

Quantum sketch

Photons, matter waves, uncertainty.

Physics

Gravity and orbits

Newton's gravity, Kepler, surface g, and circular orbits.

Physics

Rotation

Angular velocity, moment of inertia, torque, angular momentum, rolling.

Physics

SHM and resonance

Springs and pendulums, energy swap, damping, driving, and resonance.

Physics

Electrostatics

Coulomb force, electric field, potential, and a Gauss-law sketch.

Physics

Magnetostatics

Lorentz force, Biot–Savart, Ampère, and the solenoid.