Fluid Mechanics: 

Bernoulli's equation:  P + ρgh + ½ρv^{2}= constant. 
Poiseuille's law  Q = π∆Pr^{4}/(8ηL) 
Volume flow rate = π*(pressure difference)*(pipe radius)^{4}/[8*(pipe length)*viscosity)  
Kinetic Theory: 

Ideal gas law:  PV = nRT = Nk_{B}T 
Kinetic theory:  PV = (2/3)N(m<v^{2}>/2) 
Avg. kinetic energy per particle:  <KE> = (3/2)k_{B}T 
Temperature and Heat: 

Linear expansion:  Δl = αlΔT. 
Volume expansion:  ΔV = βVΔT 
Thermal conductivity:  ΔQ/Δt = kA ΔT/Δx. 
Specific heat capacity:  c = ΔQ/(m ΔT). 
Wien's law:  λ_{max } ∝ 1/T. 
StefanBoltzmann Law  Radiated power = emissivity * σ * T^{4} * Area 
Thermodynamics 

First law of thermodynamics:  ΔU = ΔQ  ΔW 
Carnot cycle:  Q_{1}/T_{1 }= Q_{2}/T_{2} 
Efficiency of a heat engine:  e = W/Q_{high }= (Q_{high } Q_{low})/Q_{high} 
COP of refrigerator:  COP = Q_{low}/(W) = Q_{low}/(Q_{high } Q_{low}) 
COP of heat pump:  COP = Q_{high}/(W) = Q_{high}/(Q_{high } Q_{low}) 
Change in entropy:  ΔS = ∫_{i}^{f} dQ_{r}/T, dS = dQ/T 
1 Cal = 1 kcal = 4186 J
k_{B} = 1.381*10^{23} J/K, R = 8.31 J/(mol K)