Where does the “2” come from in the expression for paverage? why is there no time dependence? } questions 55 – 56 consider alternating current. 55. beyond the very unfamiliar behaviors of ac circuits we have seen in the lab, what is the major reason we describe the power in an ac circuit as paverage rather than p(t)? 56. where does the “2” come from in the expression for paverage?

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )