Sort each formula into its domain: Waves, Fluids, or Thermodynamics.

Waves: $v = f\lambda$, $y = A \sin(kx - \omega t)$

Fluids: P + $\frac{1}{2} \rho v^{2}$ = const, $A_{1}v_{1} = A_{2}v_{2}$

Thermodynamics: $\Delta U = Q - W$, η = 1 − $T_c$/$T_h$

Each formula encodes a core idea from its respective subdiscipline.