Equilibrium: no net force, no acceleration, constant velocity or at rest, forces form a closed figure
Resultant force = Fnet: head-to-head and tail-to-tail with components
Equilibriant: equal and opposirte to resultant
Mass (m): inertia, amount of matter, constant from place to place - unit: kg
Weight (Fg or w):force of gravity, changes from place to place - unit: N - formula:Fg=mg
g: acceleration due to gravity - unit:m/s^2 - formula:g=GM/r^2
g: gravitaional field strength - unit:N/kg - formula:g=Fg/m
Statiic Friction (at rest): applied force until motion starts
Kinetic Friction (in motion) is constant
Maximum static friction is greater than kinetic friction - Ff=µFN
Newton's First Law: an object that is moving with a constant velocoty or is at rest has all balanced forces
Newton's Second Law: the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Newton's Third Law: every action has an opposite and equal reaction
Electricity
Conductors (metals) have free elecrrons, insulators do not.
Objects become charged by losing or gaining electrons (not protons).
Elementary Charge: proton or electron
1 Coulomb of charge = 6.35 x 10^18 elementary charges
Charge of Electron: q = -1e OR q = -1.60 x 10^-19C
Mass of Proton: m = 1.67 x 10^-27kg
If two or more identical charged spheres touch, the final charge on each is the average charge (total charge / # of spheres). The total charge is conserved.
A neutral object will be attracted (never repelled) by any charged object.
Charging by conduction: direct contact - electroscope gets same charge as rod
Charging by induction: no direct contact - electroscope gets charge opposite of rod
Electric potential difference (voltage): work done per unit charge (V = W/q)
Least resistance (best conductor): short, fat, cold
Most resistance (worst conductor): long, skinny, hot
Voltmeter: connect in parallel, infinite internal resistance
Ammeter: connect in series, zero internal resistance
1 electronvolt (eV) = 1.60 x 10^-19J
1 kilowatt hour = (1000 W)(1 hr) = 3.6 x 10^6J
An electric current (or moving charged particle) generates a magnetic field.
A changing/moving magnetic field induces an electric current (electromagnetic induction).
Waves
Transverse: perpendicular
Longitudinal: parallel
Radio Wave: electromagnetic wave - speed = 3.00 x 10^8m/s
Refraction: changing direction when changing speed when crossing a boundary
Diffraction: bending around obstacle or spreading through opening
Noticeable diffraction: when size of opening approx. equal to size of wavelength – as opening gets smaller, more diffraction effects
Resonance: energy is transferred to a system by making it vibrate at its natural frequency resulting in large amplitude standing waves - Examples: guitar string or wine glasses
Doppler Effect: apparent change in frequency due to relative motion
Polarized Light: vibrates in only one direction
Dispersion: spreading out of light into components due to refraction – each color has slightly different index and speed
Modern Physics
Photon: quantum (particle) of light
Higher frequency = Higher energy
Higher intensity = More Photons
Hadrons made of quarks, leptons don’t break down further
Antimatter = same mass, opposite charge
Alpha particle = helium nucleus (2 protons and 2 neutrons)