State and explain Newton's law of cooling.

Newton’s Law of Cooling states that the rate of temperature of the body is proportional to the difference between the temperature of the body and that of the surrounding medium. It is a reasonably accurate approximation in some circumstances.

More precisely, let T denote the temperature of an object and Tο the ambient temperature.   if t denotes time, then Newton's law states that

dT/dt  = -k(T-Tο)

where k is a positive constant. Thus, if the object temperature is much higher than its surroundings, then  T-Tο is large and positive, so dTdT/dt is large and negative, so the object cools quickly. If the object temperature is only slightly higher than its surroundings, then T-Tο is small positive, and the object cools slowly. So a cup of coffee will cool more quickly if you put it in the refrigerator! 

Newton’s Law of Cooling states that the rate of change of temperature of a body is proportional to the difference between the temperature of the body and that of the surrounding medium. It is a reasonably accurate approximation in some circumstances.

More precisely, let T denote the temperature of an object and Tο the ambient temperature.   if t denotes time, then Newton's law states that

dT/dt  = -k(T-Tο)

where k is a positive constant. Thus, if the object temperature is much higher than its surroundings, then  T-Tο is large and positive, so dTdT/dt is large and negative, so the object cools quickly. If the object temperature is only slightly higher than its surroundings, then T-Tο is small positive, and the object cools slowly. So a cup of coffee will cool more quickly if you put it in the refrigerator!