Explain Newton's law of cooling and where it is applied.

Newton's law of cooling states that the rate of convective heat transfer is proportional to the temperature difference between a surface and the surrounding fluid: Q = hA(Ts - T∞). Here, h is the convective heat transfer coefficient (W/m²-K), A is surface area, Ts is surface temperature, and T∞ is fluid temperature. This law is fundamental in designing cooling systems, HVAC equipment, electronic cooling, and any application involving fluid-surface heat exchange.