A pan of water (46 degrees) was put into a fridge. Ten min later, its temp was 39. Ten min after that, it was 33. Use newtons law of cooling. How cold was the fridge?
I know his law, but how do I find the rate?
That is a relatively simple separable differential equation which you can solve by integrating both sides of .
That will, of course, depend upon three unknown constants, k, , and the constant of integration. Fortunately, you have three equations, T(0)= 46, T(10)= 39, and T(20)= 33. You can solve those three equations for the three constants, in particular which is what you are asked.