State the Newton's law of cooling and express it mathematically?
The relationship for the energy flow rate due to convective heat transfer at the interface between a solid object and a fluid environment is referred to as Newton's Law of Cooling. If we denote the surface temperature of the solid as and the bulk fluid temperature as , then the energy transfer rate between the solid and fluid is proportional to the surface area for heat transfer, A, and the temperature difference between the solid surface and the bulk fluid temperature. The proportionality constant is often given the symbol h, which is known as the heat transfer coefficient.
In equation form, the above statement for Newton's Law of Cooling can be written as
q = hA( - )