shorter physics

Newton’s 1st Law

Objects stay at rest or in constant motion unless acted on by a net force.

Newton’s 2nd Law

Acceleration depends on force and mass. Fnet = ma

Newton’s 3rd Law

Every action force has an equal and opposite reaction force.

Weight

Force of gravity on an object. Fg = mg

Terminal velocity

When air resistance equals weight so acceleration becomes zero.

Velocity

Speed with direction.

Acceleration

Rate of change of velocity.

Free fall

Motion when gravity is the only force acting. g = 10 m/s² downward

Momentum

Quantity of motion depending on mass and velocity. p = mv

Impulse

Force applied over time that changes momentum. Ft = Δp

Elastic collision

Objects bounce apart and momentum is conserved. m₁v₁ + m₂v₂ = m₁v₁′ + m₂v₂′

Perfectly inelastic collision

Objects stick together after collision. m₁v₁ + m₂v₂ = (m₁ + m₂)vf

Work

Force causing displacement in the direction of motion. W = Fd

Kinetic energy (KE)

Energy of motion. KE = ½mv²

Potential energy (PE)

Stored energy due to position. PE = mgh

Power

Rate at which work is done or energy is transferred. P = W/t

Conservation of energy

Energy cannot be created or destroyed, only transformed.

Torque

Rotational force that causes rotation. τ = rF

Centripetal force

Inward force keeping an object moving in a circle. Fc = mv²/r

Period (T)

Time for one complete cycle. T = 1/f

Frequency (f)

Number of cycles per second. f = 1/T

Wave speed

Speed a wave travels. v = fλ

Doppler effect

Apparent change in frequency due to motion.

Voltage

Electric potential energy per charge.

Electric current

Flow of electric charge.

Resistance

Opposition to current flow.

Ohm’s Law

Relationship between voltage, current, and resistance. V = IR

Power in circuits

Rate electrical energy is transferred. P = IV

Series circuit

Same current through all components; voltage splits.

Parallel circuit

Same voltage across branches; current splits.

Density

Mass per unit volume. ρ = m/V

Pressure

Force per unit area. P = F/A

Bernoulli’s Principle

Faster-moving fluid has lower pressure.

Reflection

Angle of incidence equals angle of reflection.

Refraction

Bending of light due to speed change in a new medium.

Converging lens

Brings light rays together.

Diverging lens

Spreads light rays apart.

Plane mirror

Forms virtual upright same-size images.

Concave mirror

Can form real/inverted or virtual/upright images.

Convex mirror

Always forms virtual upright smaller images.

Additive color mixing

Red + green + blue light forms white.

Subtractive color mixing

Cyan + magenta + yellow pigments absorb colors.