Physics Equations Flashcards
Heat transferred
q = m c ΔT
Thermal expansion
ΔL = α × L × ΔT
β = 3α
Volumetric expansion
ΔV=β×V×ΔT
β = 3α
First law of thermodynamics
ΔU = Q + W
Entropy
ΔS = Qrev / T
Definition of velocity:
v = Δx / Δt
x = displacement
Definition of acceleration
a = Δv / Δt
Kinematic under constant acceleration
v = vo + at
Δx = vot + at2/2
v2 = vo2 + 2aΔx
Projectile motion
vy = vyo − ay t
Δy = vyo t − (½)at2
vy2 = vyo2 + 2ayΔy
The time for one revolution around the circle with velocity (Period of circular motion)
T = 2 π (R / vT)
Centripetal acceleration
ac = v2/r = rω2
Torque equation and units
t = r F sinθ
Units: N*m
Work-Kinetic Energy theorem
Wnet = ΔKE = Kf - Ki
Work equation and units
W = F × d × cosθ
unit = 1 Joule
Power equation and units
P = ΔW / Δt
Unit = 1 watt = J/s
Buoyant force
FB = mdisplaced × g = ρfluid × Vobject × g
Hydrostatic pressure
P = ρ × g × h
Atmospheric pressure
atm = Pa
1 atm = 101,000 Pa
Pascal’s law
F1/A1 = F2/A2 = constant
Bernoulli’s equation
P + (1/2) ρ v2 + ρ g h = constant
Coulomb’s Law
F=− k q1 q2 / r2
Electric field
E = F / q = kQ/r2
units = N/C
Electric potential
V = U/q = kQ/r
Unit: 1 volt = 1 J/C
Electric Potential Energy
U = kQq / r = Work
Unit = Joule
Electrical Current
I = ΔQ / Δt
Unit: 1 Amp: C/s
Resistivity
R = (ρ * L) / A
p = resistivity
L = length
A = cross sectional area
Unit resistance: Ohm
Unit resistivity: Ohm-meter
Ohm’s law
V = I R
Capacitance
C = Q / V
Unit = farad or C/V
Capacitance based on parallel plate geometry
C= A k ϵ0 / d
ϵ0 = 8.85 x 10-12 F/m
Potential Energy of a Capacitor
U = ½ C(ΔV)2
Magnetic force on a moving point charge
F = q × v × B × sinθ
Magnetic force on a current carrying wire
F = I × L × B × sinθ
B = Tesla = N*s / m*C
Magnification
M = h image / h object = - d image / d object
Thin lens equation
1/f = 1/p + 1/q
Photon energy
E = h × f
Double slit equation (applied to diffraction gratings)
d × sinθ = m × λ
Single slit equation
a × sinθ = m × λ
Doppler equation
f′ = (c+ν0)/(c−νs) × f
Velocity of sound
v = f × λ
Equation to find dB from intensity and Io
β = 10 log ( I / I0 )
I0 = 10−12 W/m2
Doppler effect
f′= (ν+ν0) / (ν−νs) × f
Equation for frequency and wavelength in strings and open tubes
“ I envy (nv) your tool (2L)”
String
- f = (nv) / 2L
- λ = 2L / n
- n = harmonic = antinodes (crests)
Open pipe
- f = (nv) / 2L
- λ = 2L / n
- n = harmonic = nodes (center)
Equation for wavelength and frequency in tubes with one open one closed end
λ = 4 L / n
f = n v / 4 L
n = half wavelengths
Absorbed or emitted light
1 / λ = R (1/nf2 − 1/ni2)
E = h ν = h (c/ λ)
Alpha decay
ZAX → Z-4A-4X + 24α
Beta-minus decay
ZAX → Z+1AY + -10β
Beta-plus decay
ZAX→Z−1AY+10β
Units for Pressure
Pascal
N/m2
m-1 kg s-2
Electric Charge
Coulomb (C)
units: A*s
Electric Potential
Volt (V)
W/A
m2 kg s-3 A-1
Capacitance units
Farad (F)
C/V
m-2 kg-1 s4 A2
Electric Resistance
Ohm
Volts/Amps
m2 kg s-3 A-2
Magnetic flux density
Tesla (T)
Wb/m2
kg s-2 a-1
Elastic Potential Energy
U = ½ k x2
Joule
Hooke’s Law
F = -k x
Unit: Newton
Electric field in a capacitor
E = V / d
Angular frequency equation
w = 2 pie f = 2pie /T
Equation for Gibbs with Keq
G = -2.3RT log(Keq) R= 8.3 J/k T= x kelvins
Equation for Gibbs with Keq
G = -2.3RT log(Keq) R= 8.3 J/k T= x kelvins