Newton's law of cooling states that the rate of change of temperature of an object in a surrounding medium is proportional to the difference of the temperature of the medium and the temperature of the object. suppose a metal bar, initially at temperature 50 degrees celsius, is placed in a room which is held at the constant temperature of 40 degrees celsius. one minute later the bar has cooled to 40.49787 degrees . write the differential equation that models the temperature in the bar (in degrees celsius) as a function of time (in minutes).