few general formulas

[nix85]

like title says, just some general stuff u all know in one place, feel free to add anything

λ = c/f
F = MA
momentum = mv²
Kinetic Energy ke = 1/2 mv²
centrifugal/centripetal force: F = mv²/r
point body angular momentum momentum unit: L = r x p kg m/s
Force = Mass * acceleration
Work = Change in Energy
Work = force * distance moved  unit: newton/meter or joule or Work = Mass * Gravity * Height
Power = work / time = force * displacement / time = force * velocity
Power (hp,watt) = work(ENERGY)/time aka time rate of energy transfer
Energy = Power x Time
A = V/T
f = 1/T
f = c/λ
for capacitor circuit V=C*(dv/dt)*R
XL= 2πfL
XC= -1/2πfC
Z = sqrt(R² + (Xc - Xl)²)
F = 1/6.28(LC)
F = 1/2π√LC
C=1(L*(2*pi*Fr)^2)
ohms law: V = IR
power per second:
P = IV
P = I²R copper losses
P = V²/R
true power P=VIcosφ
energy stored in an inductor E = LI²/2
energy stored in an cap E = 1/2 QV and E = CV²/2
for capacitor and inductor circuit V=IZ
1 Volt = 1 Joule/Coulomb
1 Watt = 1 Joule/Second
1W = 1V x 1A
1 Ampere = 1 Coulomb/Second
V × A = J/C × C/s = J/s = Watt
electric energy E = IVt and E = (V²/R)t
1V = 1A 1Ω
1F = 1C / 1V - amount of electric charge in coulombs that is stored per 1 volt
C = Q / V and C = kA/d
E = F / Q electric field (N/C or V/m) is force per charge
F = qE + qv x B lorentz law, em forces on a charge
R = 80*pi^2*(L/W)^2 rad. res. of antenna where L=length of antenna, and W = wavelength
τ = L/R inductor time constant, after ~5τ (transient time) current reaches 99.5%
τ = RC for RC circuit, after 5RC cap is fully charged
transformer size is proportional to B MAX =V/F
in alternator emf leads flux by 90°+
energy content of wave is proportional to the amplitude squared P ~ E2
Z = sqrt( L / C ) cable impedance
Ohm = volt / amp
reactive load temporary stores energy, not waste it (unless PS cant take it back)
v = L(di/dt) BACKEMF from an inductor
Short circuit current = V / alternator internal resistance
V=-N*dΦ/dt voltage - farraday's law
V = BLv induced voltage - farraday law for moving conductor
flux density = amper x turns x core permeability x core area / m² (T)
F = ILxB force on a conductor in a magnetic field - laplace
as load increases, current in the conductor must increase to balance the forces: I = F/BL
V = L * di/dt voltage across an inductor

[bistander]

like title says, just some general stuff u all know in one place, feel free to add anything

λ = c/f
F = MA
<snip>
Work = force * distance moved  unit: newton/meter or joule or Work = Mass * Gravity * Height
Power = work / time = force * displacement / time = force * velocity
<snip>

Where I added bold:
"newton/meter" should read "newton meter"

There can be misleading aspects of simple lists of equations like this as it can encourage people to just pick and choose without knowing proper context or fundamentals. Like difference between average values and instantaneous ones. Also confusion arising from common symbols used for different variables or units, like L for length or L for inductance.

Equations can be like computer programs: garbage in, garbage out.

Regards,
bi

[nix85]

i stand corrected about newton meter altho it is clear from preceeding formula it should be newton meter.

for rest i only partially agree, anyone unsure of the variable meaning can simply google the formula, i wanted to keep it simple

[bistander]

i stand corrected about newton meter altho it is clear from preceeding formula it should be newton meter.

for rest i only partially agree, anyone unsure of the variable meaning can simply google the formula, i wanted to keep it simple

But it is those who are not unsure who can do harm. Sorry, I'm just not in favor of a list of formulae. Even worse are rules of thumb.
Regards,
bi

[nix85]

But it is those who are not unsure who can do harm. Sorry, I'm just not in favor of a list of formulae. Even worse are rules of thumb.
Regards,
bi

well, it is sure best for everyone to build their own list of formulas so there is no confusion to what each variable means