Question

The approximate rate equation for convective heat transfer between a surface and adjacent fluid is calculated by:

• A. Newton’s law of Cooling
• B. Kirchhoff’s law
• C. Newton’s first law
• D. Wein’s displacement law

Hint:

While called a "law," Newton's Law of Cooling is actually a defining equation for the convection coefficient $h$, which is not a property of the fluid but depends on the flow conditions and geometry.

Answer 1

The Correct Option is A

Heat transfer between a hot surface and the fluid moving past it is usually written as \( Q = hA(T_s - T_f) \), a simple linear relationship between the temperature gap and the rate of heat loss, with \( h \) capturing how effectively the fluid carries heat away. This particular linear relationship for convective heat transfer is named after Newton and is called Newton's law of cooling. Kirchhoff's law and Wien's law deal with radiation instead, and Newton's first law is about mechanics, not heat, so none of those apply here.